Absorbent article and method for manufacturing same

ABSTRACT

In order to prevent degradation of appearance, prevent a decrease in flexibility, and improve non-elasticity in a non-stretchable region in an elastic film stretchable structure, the invention is characterized by having an elastic film stretchable structure (20X) formed by stacking an elastic film (30) between a first sheet layer (20A) and a second sheet layer (20B), wherein a region having the elastic film stretchable structure (20X) includes a non-stretchable region (70) and a stretchable region (80) provided at least at one side of the non-stretchable region (70) in a stretching and contracting direction, the stretchable region (80) being stretchable in the stretching and contracting direction, the first sheet layer (20A) and the second sheet layer (20B) are joined via through holes (31) penetrating the elastic film (30) at the large number of sheet bond portions (40) arranged at intervals, and the non-stretchable region (70) does not have a section in which the elastic film (30) linearly continues along the stretching and contracting direction, due to presence of the through holes (31), even though the elastic film (30) continues in the stretching and contracting direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of co-pending application Ser. No.15/547,019, filed on Jul. 27, 2017, for which priority is claimed under35 U.S.C. § 120; and this application claims priority of Application No.2015-017498 filed in Japan on Jan. 30, 2015, Application No. 2015-067324filed in Japan on Mar. 27, 2015, Application No. 2015-071784 filed inJapan on Mar. 31, 2015, Application No. 2015-071786 filed in Japan onMar. 31, 2015, and Application No. 2015-195458 filed in Japan on Sep.30, 2015 under 35 U.S.C. § 119, the entire contents of all of which arehereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an absorbent article having astretchable structure in which an elastic film such as an elastic filmis interposed between a first sheet layer and a second sheet layer, anda method of manufacturing the same.

BACKGROUND ART

In absorbent articles, elastic characteristics are typically imparted toleg portions, waist portions, and the like to improve fitness to thesurfaces of bodies. A typical approach to impart elastic characteristicsis fixing of elongated elastically stretchable members, such as rubberthreads, in a state stretched in the longitudinal direction. In order toimpart elasticity over a certain range of width, rubber threads aredisposed and fixed in the width direction at intervals in someembodiments. In addition, an approach to impart excellent surfacefitting is fixing of elastic film in a state stretched in a direction ofimparting elasticity (for example, see Patent Literature 1).

According to a stretchable structure using the elastic film (hereinafteralso referred to as an elastic film stretchable structure), astretchable region is composed of a first sheet layer, a second sheetlayer, and an elastic film interposed therebetween, and the first sheetlayer and the second sheet layer are joined via through holes formed inthe elastic film at a large number of dot-like sheet bond portionsarranged at intervals in a stretching and contracting direction and adirection orthogonal thereto while the elastic film is stretched in thestretching and contracting direction along the surfaces of the firstsheet layer and the second sheet layer. In such an elastic filmstretchable structure, in a natural length state, as the elastic filmcontracts among the sheet bond portions, an interval between the twoadjacent sheet bond portions is decreased, and a contraction wrinkleextending in the direction orthogonal to the stretching and contractingdirection is formed between the sheet bond portions in the first sheetlayer and the second sheet layer. On the contrary, in a stretched state,as the elastic film is stretched between the sheet bond portions, theinterval between the two adjacent sheet bond portions is increased andthe contraction wrinkle in the first sheet layer and the second sheetlayer is stretched, and elastic stretching is allowed so that the firstsheet layer and the second sheet layer can be fully spread. This elasticfilm stretchable structure has advantages as follows: surface fitness isexcellent; the first sheet layer and the second sheet layer are notjoined to the elastic film and joined each other but at an extremely lowlevel, thus the elastic film stretchable structure has a satisfactoryflexibility; and the through holes of the elastic film contribute toimprovement in air permeability.

In order to simplify the manufacture of absorbent articles having astretchable region only at a given position, an approach has beenadopted which involves fixing elastically stretchable members in a largearea including the stretchable region imparting elasticity, andperforming a process to reduce or eliminate the contraction force of theelastically stretchable members to form a non-stretchable regionrequiring no elasticity (hereinafter also referred to as eliminatingelasticity). For example, to impart elasticity in the width direction tothe waist portion of an underpants-type disposable diaper, a typicalapproach has been widely adopted which involves fixing elongatedelastically stretchable members over the entire width direction, andcutting some of elastically stretchable members overlapping with anabsorber disposed at a middle of the width direction into smallfractions to eliminate the elasticity of the elastically stretchablemembers, the non-stretchable region is thereby formed.

However, when such an approach to eliminate the elasticity of thestretchable structure including rubber threads by cutting the rubberthreads is applied to the elastic film stretchable structure withoutchange, the whole elastic film becomes to be cut in the directionorthogonal to the stretching and contracting direction at least in thenon-stretchable region, and continuous cutting is required in a largearea. Thus, there is a concern that the first sheet layer and the secondsheet layer may be cut, or a concern that a cutting trace (a meltingtrace or pressing trace) may be continuously left in the first sheetlayer and the second sheet layer even when the first sheet layer and thesecond sheet layer are not cut. In addition, it is difficult tomanufacture.

CITATION LIST Patent Literature

Patent Literature 1: JP 2004-532758 A

SUMMARY OF INVENTION Technical Problem

In this regard, a main object of the invention is to provide a novelnon-stretchable region in an elastic film stretchable structure and amethod of forming the same.

Solution to Problem

The invention solving the above-mentioned problem is described below.

An absorbent article having an absorber that absorbs excrement, theabsorbent article comprising

-   -   an elastic film stretchable structure in which an elastic film        is stacked between a first sheet layer and a second sheet layer,        and the first sheet layer and the second sheet layer are joined        via through holes penetrating the elastic film at a large number        of sheet bond portions arranged at intervals, wherein    -   a region having the elastic film stretchable structure includes        a stretchable region stretchable in one direction and a        non-stretchable region provided at least at one side of the        stretchable region in a stretching and contracting direction,    -   the stretchable region has a section in which the elastic film        linearly continues along the stretching and contracting        direction,    -   the stretchable region is contracted in the stretching and        contracting direction by a contraction force of the elastic film        while it is possible that the stretchable region is stretched in        the stretching and contracting direction, and    -   the non-stretchable region, due to presence of the through        holes, does not have a section in which the elastic film        linearly continues along the stretching and contracting        direction, even though the elastic film of the non-stretchable        region continues in the stretching and contracting direction.

(Operational Advantage)

In the elastic film stretchable structure according to the invention,the section in which the elastic film linearly continues along thestretching and contracting direction has elasticity due to stretchingand contracting of such a continued site. However, in a section in whichthe elastic film does not linearly continue along the stretching andcontracting direction, the contraction force of the elastic film hardlyacts on the first sheet layer and the second sheet layer, thus,elasticity is almost lost, and an elongation at an elastic limitapproaches 100%. Therefore, it is possible to form the stretchableregion and the non-stretchable region depending on the presence orabsence of the section in which the elastic film does not linearlycontinue along the stretching and contracting direction.

Further, in such a non-stretchable region, the first sheet layer and thesecond sheet layer joined at the large number of sheet bond portionsarranged at intervals, and the sheet bond portions are discontinuous.Thus, a decrease in the flexibility is prevented. In addition, in thenon-stretchable region, continuity of the elastic film remains, anindependent cut piece of the elastic film is not left, and a wrinkle ishardly formed. Thus, appearance is extremely excellent, and airpermeability in the thickness direction by the through holes is ensured.Despite that, elasticity may be almost eliminated. In other words,according to the invention, it is possible to prevent degradation ofappearance, prevent a decrease in flexibility, and improvenon-elasticity in the non-stretchable region having the elastic filmstretchable structure.

The absorbent article, wherein

-   -   across the whole non-stretchable region, the through holes        penetrating the elastic film are disposed in a staggered shape,    -   a center-to-center interval of the adjacent two through holes in        the stretching and contracting direction is shorter than a        length of each of the through holes in the stretching and        contracting direction, and    -   a center-to-center interval of the adjacent two through holes in        a direction orthogonal to the stretching and contracting        direction is shorter than a length of each of the through holes        in the direction orthogonal to the stretching and contracting        direction.

(Operational Advantage)

When the through holes are formed in the elastic film in an intermittentpattern as described, it is possible to substantially completelyeliminate the linear continuity in the stretching and contractingdirection while maintaining continuity of the elastic film, which ispreferable. The term “center-to-center interval” refers to, when anobject is not a point symmetry figure, an interval between a center ofgravity to a center of gravity (the same applies hereinafter).

The absorbent article, wherein

-   -   a stretching stress of the elastic film is in a range of 4 to 12        N/35 mm when the elastic film is stretched four times in the        stretching and contracting direction, and    -   in a state in which the non-stretchable region is stretched to        an elastic limit in the stretching and contracting direction,        the center-to-center interval of the adjacent two through holes        in the stretching and contracting direction is in a range of 0.7        to 3.0 mm, the length of each of the through holes in the        stretching and contracting direction is in a range of 1.0 to 4.5        mm, the center-to-center interval of the adjacent two through        holes in the direction orthogonal to the stretching and        contracting direction is in a range of 1.2 to 5.25 mm, and the        length of each of the through holes in the direction orthogonal        to the stretching and contracting direction is in a range of 0.7        to 3.0 mm.

(Operational Advantage)

When the elastic film within the range as described is used, in thenon-stretchable region, dimensions of each through hole and anarrangement interval of the through holes are preferably within theranges as described. In a state in which the non-stretchable region isstretched to an elastic limit in the stretching and contractingdirection (in other words, in a state in which the first sheet layer andthe second sheet layer are fully spread), the center-to-center intervalof the adjacent two through holes in the stretching and contractingdirection is equal to a center-to-center interval of the adjacent twosheet joint portions in the stretching and contracting direction, thecenter-to-center interval of the adjacent two through holes in thedirection orthogonal to the stretching and contracting direction isequal to the center-to-center interval of the adjacent two sheet bondportions in the direction orthogonal to the stretching and contractingdirection, and the length of the through holes in the directionorthogonal to the stretching and contracting direction is equal to thelength of the sheet bond portions in the direction orthogonal to thestretching and contracting direction.

The absorbent article, wherein

-   -   in the non-stretchable region, the first sheet layer is not and        the second sheet layer is not joined to the elastic film in a        portion other than between the first sheet layer and the second        sheet layer in the sheet bond portions, and in a natural length        state, a gap is provided, which is generated so as to contain        both side portions of each of the sheet bond portions in the        stretching and contracting direction by a peripheral edge of        each of the through holes of the elastic film and each of the        sheet bond portions separated from each other.

(Operational Advantage)

When such a gap is formed in the non-stretchable region, airpermeability is imparted due to the gap even when a material of theelastic film is a non-porous film or a sheet, which is preferable.

The absorbent article, wherein

-   -   in the stretchable region, an elongation at an elastic limit in        the stretching and contracting direction is set to 200% or more,        and    -   in the non-stretchable region, an elongation at an elastic limit        in the stretching and contracting direction is set to 120% or        less.

(Operational Advantage)

The elongations at the elastic limits in the stretchable region and thenon-stretchable region may be appropriately determined. However, theelongations at the elastic limits are preferably within the ranges asdescribed.

The absorbent article, wherein

-   -   the absorbent article is an underpants-type disposable diaper        having    -   an outer body included in a front body and a back body,    -   an inner body that is fixed to the outer body and includes an        absorber, wherein    -   both side portions of the front body of the outer body are        respectively joined to both side portions of the back body of        the outer body to define side seal portions, and an annular        torso region, a waist opening, and a pair of right and left leg        openings are thereby formed,    -   the torso region of the outer body in at least one of the front        body and the back body includes an absorber region defined as a        front-back direction range overlapping the absorber,    -   the elastic film stretchable structure is disposed across a        width direction range at least of the absorber region        corresponding to a range between both the side seal portions        such that the stretching and contracting direction of the        elastic film stretchable structure corresponds to a width        direction thereof, and    -   in the absorber region, the non-stretchable region is defined as        an intermediate portion of the absorber region in the width        direction, and the stretchable region is defined as a width        direction range corresponding to a range between the        non-stretchable region and the side seal portion.

(Operational Advantage)

It is unnecessary to impart elasticity to a portion of the outer body ofthe underpants-type disposable diaper which is overlapping the absorbereven though the elastic film is desirably disposed on the portion due toa manufacturing reason. Therefore, it is preferable to form thenon-stretchable region having a display portion, including the portionoverlapping the absorber.

The absorbent article, wherein

-   -   the elastic film stretchable structure is not extended to the        waist end portion region, and    -   a whole width direction range corresponding to a range between        both the side seal portions of the waist end portion region        contracts in the width direction by a contraction force of an        elongated waist end portion elastic member attached to the whole        width direction range along the width direction while it is        possible that the whole width direction range corresponding to        the range between the side seal portions of the waist end        portion region is stretched in the width direction.

(Operational Advantage)

It is possible to provide a stretchable structure according to aconventional elongated elastically stretchable member as necessarywithout providing the elastic film stretchable structure in the waistend portion region in a case in which tightening of the waist endportion region is insufficient even with the elastic film stretchablestructure used in the waist end portion region, etc.

An absorbent article comprising

-   -   an elastic film stretchable structure formed by stacking an        elastic film between a first sheet layer and a second sheet        layer, wherein    -   a region having the elastic film stretchable structure includes        a stretchable region stretchable at least in one direction and a        non-stretchable region being provided at least at one side of        the stretchable region in a stretching and contracting direction        and having an elongation at an elastic limit in the stretching        and contracting direction of 130% or less,    -   in the stretchable region, in a state in which the elastic film        is stretched in the stretching and contracting direction, the        first sheet layer and the second sheet layer are directly or        indirectly joined at a large number of sheet bond portions        arranged at intervals in each of the stretching and contracting        direction and a direction orthogonal thereto,    -   in the non-stretchable region, the first sheet layer and the        second sheet layer are joined by welding at sheet bond portions        provided in a row extending in a dotted line in a direction        intersecting the stretching and contracting direction or in a        plurality of rows, each of which is extending in a dotted line        in a direction intersecting the stretching and contracting        direction, and which are extending in dotted lines disposed at        intervals in the stretching and contracting direction, the        elastic film is cut along the row of the sheet bond portions,        and both side portions of a cut position of the elastic film are        left at both sides of the row of the sheet bond portions in the        stretching and contracting direction in a natural length state,        and    -   a cut portion of the elastic film is formed by fracture of        perforation formed by melting on the elastic film.

(Operational Advantage)

As an approach to eliminate the elasticity of the elastic filmstretchable structure, it has been found that elasticity may besubstantially eliminated by increasing the area rate of the sheet bondportions (per unit area) to some extent or more. However, to this end,the area rate of the sheet bond portions needs to be significantlyincreased, and hardening of touch may not be avoided.

In the non-stretchable region of the invention, the first sheet layerand the second sheet layer are joined by welding at sheet bond portionsprovided in a row extending in a dotted line in a direction intersectingthe stretching and contracting direction or in a plurality of rowsextending in dotted lines in a direction intersecting the stretching andcontracting direction and disposed at intervals in the stretching andcontracting direction. Therefore, even though the first sheet layer andthe second sheet layer are integrated by welding at the sheet bondportions, since the sheet bond portions are discontinuous, a decrease inflexibility is prevented. Meanwhile, the elastic film is cut along therows of the sheet joint portions, and both side portions of a cutposition of the elastic film are left at both sides of the rows of thesheet joint portions in the stretching and contracting direction in anatural length state. Therefore, in the non-stretchable region, theelasticity of the elastic film is reliably eliminated and the elasticfilm is discontinuous, resulting in high air permeability. Further, thecut portion of the elastic film is formed by fracture of perforationformed by melting on the elastic film. That is to say, since the cutportion resulting from melting is discontinuous, a trace of cuttingresulting from melting is discontinuous. Therefore, appearance isexcellent, and a decrease in flexibility may be prevented.

The absorbent article, wherein

-   -   in the non-stretchable region, the plurality of rows of the        sheet bond portions is provided at intervals in the stretching        and contracting direction, the both side portions of the cut        positions of the elastic film are left as cut pieces in the        natural length state so as to cross every other row in the rows        of the sheet bond portions in the stretching and contracting        direction, and the first sheet layer and the second sheet layer        are joined via through holes provided in the cut pieces of the        elastic film at sites of the rows of the sheet bond portions.

(Operational Advantage)

According to such a structure, since the cut pieces of the elastic filmare fixed by joining the first sheet layer and the second sheet layer,the cut piece may be prevented from moving to degrade appearance orwearing feeling.

The absorbent article, wherein

-   -   the absorbent article is an underpants-type disposable diaper        having an outer body included in a front body and a back body,        an inner body that is fixed to an internal surface of the outer        body and includes an absorber, wherein both side portions of the        front body of the outer body are respectively joined to both        side portions of the back body of the outer body to define side        seal portions, and an annular torso region, a waist opening, and        a pair of right and left leg openings are thereby formed,    -   the outer body in at least one of the front body and the back        body includes the elastic film stretchable structure disposed        across a width direction range corresponding to a range between        both the side seal portions at least in a part of a front-back        direction range of the side seal portion such that the        stretching and contracting direction of the elastic film        stretchable structure corresponds to a width direction, and    -   a region including the elastic film stretchable structure has        the non-stretchable region in a region overlapping the absorber,        and the stretchable regions at both sides of the non-stretchable        region in the width direction.

(Operational Advantage)

The underpants-type disposable diaper has the stretchable region and thenon-stretchable region in a large area, and thus is particularlysuitable for the invention.

A method of manufacturing an absorbent article comprising

-   -   an elastic film stretchable structure formed by stacking an        elastic film between a first sheet layer and a second sheet        layer, wherein    -   a region including the elastic film stretchable structure has a        stretchable region stretchable at least in one direction and a        non-stretchable region being provided at least at one side of        the stretchable region in a stretching and contracting direction        and having an elongation at an elastic limit in the stretching        and contracting direction of 130% or less,    -   the method comprising    -   in forming the elastic film stretchable structure, in a state        the elastic film is stacked between the first sheet layer and        the second sheet layer while the elastic film is stretched in an        MD (Machine Direction),    -   in the stretchable region, forming sheet bond portions by        joining the first sheet layer and the second sheet layer at a        large number of positions arranged at intervals in each of the        MD and a CD (Cross Direction) orthogonal to the MD, and    -   in the non-stretchable region, performing a welding process in a        welding pattern of one row extending in a dotted line in the CD        or a plurality of rows, each of which is extending in a dotted        line in the CD, and which are disposed at intervals in the MD,        to melt the elastic film in the welding pattern of the dotted        line, thereby forming perforation, joining the first sheet layer        and the second sheet layer via through holes of the perforation        to form sheet bond portions, and then fracturing the perforation        by a tensile force applied by stretching of the elastic film.

(Operational Advantage)

As stated above, in the non-stretchable region, the perforationresulting from melting is formed in the elastic film by performing thewelding process in the welding pattern of the one row or the pluralityof rows, each of which is extending in a dotted line in the CD, andwhich are disposed at intervals in the MD, in the state in which theelastic film is stacked between the first sheet layer and the secondsheet layer while the elastic film is stretched at least in the MD, andat the same time, the first sheet layer and the second sheet layer arejoined via the through holes of the perforation, and further, theperforation is fractured by the tensile force applied by stretching theelastic film. Therefore, it is possible to significantly simply andefficiently form the non-stretchable region as described.

The method of manufacturing an absorbent article, wherein

-   -   in the non-stretchable region, the welding process is set to        perform in the welding pattern of the plurality of rows disposed        at intervals in the MD, the perforation is formed in a welding        pattern of the rows, each of which is extending in the dotted        line, and which are located every other row in the MD, and is        fractured by the tensile force applied by stretching of the        elastic film, and cut pieces of the elastic film are left in a        natural length state so as to cross the remained rows in a        welding pattern of the rows, each of which is extending in the        dotted line, and the remained rows locating every other row of        the sheet bond portions.

(Operational Advantage)

It is possible to significantly simply and efficiently form thenon-stretchable region as described.

The method of manufacturing an absorbent article, wherein

-   -   the elastic film is an elastic film having a tensile strength in        the MD of 8 to 25 N/35 mm, a tensile strength in the CD of 5 to        20 N/35 mm, a tensile elongation in the MD of 450 to 1,050%, and        a tensile elongation in the CD of 450 to 1,400%, and    -   in performing the welding process, the welding pattern of the        row extending in the dotted line is set to a pattern having an        interval in the CD between the two adjacent welding points of 1        mm or less, and the elastic film is put in a state in which the        same is stretched 2 to 5 times in the MD.

(Operational Advantage)

The elastic film is not particularly restricted. However, an elasticfilm having the above-described characteristic is preferable. In thiscase, in performing the welding process, the welding pattern and to thenumber of times in the length the elastic film is stretched arepreferably in the above-described ranges for reliable fracture of theperforation of the elastic film.

The method of manufacturing an absorbent article, wherein

-   -   the welding process is performed by a welding process device on        a production line while the first sheet layer, the second sheet        layer, and the elastic film are continuously conveyed on the        production line, and    -   the welding pattern of the dotted line is set to have a section        in which the interval in the CD between the two adjacent welding        points is a first interval, and a section in which the interval        in the CD between the two adjacent welding points is a second        interval being larger than the first interval.

(Operational Advantage)

When the welding pattern of the dotted line described above is adopted,ties of perforation (tying portions each of which is provided betweenthe two adjacent through holes) formed in the elastic film become tieseach having the same length as that of the first interval and ties eachhaving the same length as that of the second interval. When theperforation is fractured by the tensile force applied by stretching theelastic film, the ties each having the same length as that of the firstinterval are first fractured, and then the ties each having the samelength as that of the second interval are fractured. Accordingly, it ispossible to increase time taken from the welding process to fracturingthe whole of the perforation of the elastic film. Therefore, a situationcan be prevented in which the perforation of the elastic film isfractured almost at the same time that the welding process is performedand thus the elastic film cannot be continuously conveyed.

An absorbent article comprising

-   -   an elastic film stretchable structure in which    -   an elastic film is stacked between a first sheet layer and a        second sheet layer,    -   in a state in which the elastic film is stretched in the        stretching and contracting direction along surfaces of the first        sheet layer and the second sheet layer, the first sheet layer        and the second sheet layer are joined via through holes formed        in the elastic film at a large number of sheet bond portions        arranged at intervals in each of a stretching and contracting        direction and a direction orthogonal thereto, wherein    -   a region including the elastic film stretchable structure has a        non-stretchable region and a stretchable region being provided        at least at one side of the non-stretchable region in the        stretching and contracting direction and being stretchable in        the stretching and contracting direction, and    -   in the non-stretchable region, an area rate of the sheet bond        portions in the non-stretchable region is higher than that in        the stretchable region and elasticity of the elastic film at a        part or total of a portion formed among the through holes is        decreased due to thermal deterioration, thereby an elongation at        an elastic limit is set to 130% or less in the stretching and        contracting direction.

(Operational Advantage)

Through examination of approaches to eliminate the elasticity of theelastic film stretchable structure, in a method of performing welding ata large number of positions arranged at intervals in each of thestretching and contracting direction and the direction orthogonalthereto in a state in which the elastic film is interposed between thefirst sheet layer and the second sheet layer while the elastic film isstretched in the stretching and contracting direction of the stretchableregion to melt the elastic film at the plurality of positions, therebyforming the through holes, as well as joining the first sheet layer andthe second sheet layer at positions of the through holes for forming theelastic film stretchable structure, it has been found that theelasticity can be substantially eliminated by making the area rate (perunit area) of the sheet joint portions to be higher than a certainlevel. That is to say, in such an elastic film stretchable structure,basically, the larger the area rate of the sheet joint portions is, thesmaller area of a portion formed among the through holes is, since ineach of the portions, the first sheet layer and the second sheet layercontract by the elastic film. Thus, the elongation at the elastic limittends to decrease. Further, when the area rate of the sheet jointportions is higher than or equal to a certain level, elasticity issubstantially lost, and non-elasticity is obtained since the elongationat the elastic limit decreases, as well as the most of the portionformed among the through holes of the elastic film deteriorates due toheat generated in the welding. Therefore, according to the invention,while the elasticity is substantially eliminated, continuity of theelastic film in the stretchable region and the non-stretchable regioncan be maintained and can produce an absorbent article having a goodappearance.

The absorbent article, wherein

-   -   the absorbent article is an underpants-type disposable diaper        having    -   an outer body included in a front body and a back body,    -   an inner body that is fixed to an internal surface of the outer        body and includes an absorber, wherein    -   both side portions of the front body of the outer body are        respectively joined to both side portions of the back body of        the outer body to define side seal portions, and an annular        torso region, a waist opening, and a pair of right and left leg        openings are thereby formed,    -   the outer body in at least one of the front body and the back        body includes the elastic film stretchable structure disposed        across a width direction range corresponding to a range between        both the side seal portions at least in a part of a front-back        direction range of the side seal portion such that the        stretching and contracting direction of the elastic film        stretchable structure corresponds to a width direction, and    -   a region including the elastic film stretchable structure has        the non-stretchable region in a region overlapping the absorber,        and the stretchable regions at both sides of the non-stretchable        region in the width direction.

(Operational Advantage)

The invention is particularly suitable for the underpants-typedisposable diaper.

A method of manufacturing an absorbent article comprising

-   -   an elastic film stretchable structure in which an elastic film        is stacked between a first sheet layer and a second sheet layer,        and in a state in which the elastic film is stretched in the        stretching and contracting direction along surfaces of the first        sheet layer and the second sheet layer, the first sheet layer        and the second sheet layer are joined via through holes formed        in the elastic film at a large number of sheet bond portions        arranged at intervals in each of a stretching and contracting        direction and a direction orthogonal thereto, wherein    -   a region including the elastic film stretchable structure has a        non-stretchable region and a stretchable region being provided        at least at one side of the non-stretchable region in a        stretching and contracting direction and being stretchable in        the stretching and contracting direction, and    -   the method comprising:    -   in forming the elastic film stretchable structure, in a state in        which the elastic film is stacked between the first sheet layer        and the second sheet layer while the elastic film is stretched        in an MD (Machine Direction), welding the first sheet layer and        the second sheet layer at a large number of positions arranged        at intervals in each of the MD and a CD (Cross Direction)        orthogonal to the MD, and melting the elastic film at the large        number of positions so as to form through holes, joining the        first sheet layer and the second sheet layer at least by        solidification of a melted material of the elastic film at        positions of the through holes; and    -   in the non-stretchable region, in the welding, making an area        rate of the sheet bond portions in the non-stretchable region to        be higher than in the stretchable region, and transferring heat        generated in the welding to a part or total of a portion formed        among the through holes in the elastic film to degrade the part        or total of the portion formed among the through holes using the        heat generated in the welding to decrease elasticity.

(Operational Advantage)

When welding is performed by heat sealing, ultrasonic sealing, etc. inan arrangement pattern of the sheet joint portions in a state in whichthe elastic film is interposed between the first sheet layer and thesecond sheet layer as described above, the through holes of the elasticfilm can be formed in any one of the stretchable region and thenon-stretchable region, as well as the first sheet layer and the secondsheet layer can be joined by solidification of the melted material ofthe elastic film via the through holes. Furthermore, since the area rateof the sheet joint portions in the non-stretchable region is higher thanthat in the stretchable region, simultaneously with formation of thethrough holes and the sheet joint portions, heat generated in thewelding can be transferred to the part or whole of the portion formedamong the through holes in the elastic film to degrade the part or wholeof the portion formed among the through holes by the heat generated inthe welding, thereby decreasing elasticity. Therefore, it is possible tosignificantly simply and efficiently manufacture the elastic filmstretchable structure having the stretchable region and thenon-stretchable region. In addition, the manufactured stretchable regionachieves both high air permeability and high peeling strength.

The method of manufacturing an absorbent article, wherein

-   -   the welding corresponds to ultrasonic welding,    -   an area of each of the sheet joint portions in the        non-stretchable region is in a range of 0.14 to 0.75 mm², and

an area rate of the sheet bond portions in the non-stretchable region isin a range of 8 to 17%.

(Operational Advantage)

As described above, in a case in which, the ultrasonic welding is usedin order to form the through holes and the sheet joint portions, and theheat generated in the welding is used in order to decrease elasticity ofthe non-stretchable region, under a condition that a speed of aproduction line is low (about 30 m/min), ultrasonic vibration is easilytransferred, and a sufficient thermal deterioration area of the elasticfilm may be ensured by increasing the area of each of the sheet jointportions in the non-stretchable region to some extent. However, under acondition that the speed of the production line is high (about 120m/min), there is a concern that welding of the sheet joint portions maybe insufficient as long as the area of each of the sheet joint portionsis not decreased to some extent. Nevertheless, if the area of each ofthe sheet joint portions is decreased just for sufficient welding of thesheet joint portions, there is a concern that the thermal deteriorationarea of the elastic film may be insufficient for obtainingnon-stretching. On the other hand, when the ultrasonic welding isperformed by densely disposing small sheet joint portions at narrowintervals as described above, there is little concern about insufficientwelding. Further, even though the thermal deterioration area of theelastic film is small, an interval of the adjacent two through holesnarrows, and thus non-stretching is sufficiently obtained.

The method of manufacturing an absorbent article, wherein a shape ofeach of the sheet bond portions is a shape which is elongated in the MD.

(Operational Advantage)

when the shape of each of the sheet joint portions, that is, a shape ofeach of the welding portion in a welding pattern in the ultrasonicwelding is the shape that is elongated in the MD as described above, itis possible to widen the thermal deterioration area of the elastic filmwhen compared with an isotropic shape having the same area, as well asan area in which the ultrasonic vibration is applied does not increase.Thus, there is an advantage that welding of the sheet bond portions isless likely to be insufficient.

An absorbent article having an absorber that absorbs excrement, theabsorbent article comprising

-   -   an elastic film stretchable structure in which an elastic film        is stacked between a first sheet layer and a second sheet layer,        wherein    -   a region having the elastic film stretchable structure includes        a non-stretchable region and a stretchable region provided at        least at one side of the stretchable region in a stretching and        contracting direction and being stretchable in the stretching        and contracting direction,    -   in the stretchable region, in a state in which the elastic film        is stretched in the stretching and contracting direction along        surfaces of the first sheet layer and the second sheet layer, an        elongation at an elastic limit in the stretching and contracting        direction is set to 200% or more by directly or indirectly        joining the first sheet layer and the second sheet layer at a        large number of sheet bond portions arranged at intervals in        each of the stretching and contracting direction and a direction        orthogonal thereto, and    -   in the non-stretchable region, in a state in which the elastic        film is stretched in the stretching and contracting direction        along the surfaces of the first sheet layer and the second sheet        layer, an elongation at an elastic limit is set to 130% or less        by directly or indirectly joining the first sheet layer and the        second sheet layer at a large number of sheet bond portions        arranged at intervals in each of the stretching and contracting        direction and the direction orthogonal thereto and at least one        of by an area rate of the sheet bond portions in the        non-stretchable region being higher than that in the stretchable        region; the elastic film being melted; and the elastic film        being finely divided at least in the stretching and contracting        direction.

(Operational Advantage)

In the elastic film stretchable structure in the invention, when thefirst sheet layer and the second sheet layer are joined directly orindirectly at a large number of sheet bond portions arranged atintervals in each of the stretching and contracting direction and thedirection orthogonal thereto in a state in which the elastic film isstretched in the stretching and contracting direction along surfaces ofthe first sheet layer and the second sheet layer, basically, as the arearate of the sheet bond portions increases, portions in which the firstsheet layer and the second sheet layer contract by the elastic filmdecrease Thus, the elongation at the elastic limit tends to decrease.Therefore, the non-stretchable region and the stretchable region may beformed only by changing the area rate of the sheet bond portions.

In addition, the non-stretchable region may be formed by heating andmelting the elastic film or by the elastic film being finely divided atleast in the stretching and contracting direction.

The absorbent article, wherein

-   -   a display portion composed of the sheet bond portions formed by        directly or indirectly joining the first sheet layer and the        second sheet layer is included in middle in the direction        orthogonal to the stretching and contracting direction, and the        stretchable region is not included at both sides of the        non-stretchable region in the direction orthogonal to the        stretching and contracting direction.

(Operational Advantage)

The inventor has found that displays known in the field of absorbentarticles, for example, decorative patterns, such as small illustrationsand characters, functional indicators indicating usage instructions,usage guides, and sizes, and marks indicating manufacturers, productnames, and distinctive functions, etc. may be applied to the regionhaving the stretchable structure by arranging dot-shaped sheet bondportions in a display manner or by forming the sheet bond portion in ashape of the display manner in a research process of such an elasticfilm stretchable structure. An approach to apply the display is allowedsince the elastic film is continuously present in the elastic filmstretchable structure unlike a conventional stretchable structure usingrubber thread, so that arrangement and a shape of the sheet bondportions have some extent of freedom.

However, when such a display is provided in the stretchable region, thedisplay (sheet bond portions) may be hidden in a contraction wrinkle, ora relative position changes due to stretching or contracting of thestretchable region, and thus problems are caused with the appearancedepending on the content of the display and the purpose of display. Tosolve these problems, it has been considered that elasticity of adisplay formation region is eliminated to use the region as thenon-stretchable region, and a display is provided in thisnon-stretchable region. However, when the stretchable region is providedadjacent to the non-stretchable region in the direction orthogonal tothe stretching and contracting direction, a wrinkle or a pleat is formedin the non-stretchable region due to an influence of contraction of thestretchable region, and appearance of the display deteriorates.

In this regard, the invention as described proposes improvement inappearance when a display including the sheet bond portions is appliedto the elastic film stretchable structure. In more detail, in a case inwhich the non-stretchable region is formed in the elastic filmstretchable structure, and the display composed of the sheet bondportions is applied thereto, when a configuration in which thestretchable region according to the elastic film stretchable structureis not present at both sides of the non-stretchable region in thedirection orthogonal to the stretching and contracting direction isadopted, and a display portion composed of the sheet bond portions isdisposed in the middle part in the direction orthogonal to thestretching and contracting direction as described above, the displayportion is hardly affected by contraction of the stretchable region, anddeterioration of appearance of the display is prevented.

The absorbent article, wherein the sheet bond portions are formed bywelding materials of the first sheet layer and the second sheet layer.

(Operational Advantage)

A method of forming the sheet bond portions is not particularlyrestricted. However, when the sheet bond portions are formed by thewelding process, appearance of the sheet bond portions is different froma surrounding appearance. Thus, the display portion is highlighted.

The absorbent article, wherein the first sheet layer and the secondsheet layer are joined via through portions formed in an elastic sheetlayer at the sheet bond portions, and the first sheet layer is not andthe second sheet layer is not joined to the elastic film in a portionother than between the first sheet layer and the second sheet layer inthe sheet bond portions.

(Operational Advantage)

When such a structure is adopted, it is preferable that since a gap isformed by each through portion of the elastic sheet layer and each sheetbond portion, even if the elastic film layer is composed of a nonporousmaterial, the gap contributes to air permeability.

The absorbent article, wherein

-   -   in the non-stretchable region, the area rate of the sheet bond        portions is higher than that in the stretchable region so that        an elongation at an elastic limit in the stretching and        contracting direction is set to 130% or less,    -   an area of each of the sheet bond portions is in a range of 0.14        to 3.5 mm²,    -   in the non-stretchable region, the area rate of the sheet bond        portions is in a range of 16 to 45%, and    -   in the stretchable region, the area rate of the sheet bond        portions is in a range of 1.8 to 22.5%.

(Operational Advantage)

The area of each of the sheet bond portions and the area rate of sheetbond portions may be appropriately determined. However, in general, theabove ranges are desirable.

The absorbent article, wherein

-   -   the absorbent article is an underpants-type disposable diaper        having    -   an outer body included in front body and a back body,    -   an inner body that is fixed to an internal surface of the outer        body and includes an absorber, wherein    -   both side portions of the front body of the outer body are        respectively joined to both side portions of the back body of        the outer body to define side seal portions, and an annular        torso region, a waist opening, and a pair of right and left leg        openings are thereby formed,    -   the outer body in at least one of the front body and the back        body includes the elastic film stretchable structure disposed        across a width direction range corresponding to a range between        both the side seal portions at least in a part of a front-back        direction range of the side seal portion such that the        stretching and contracting direction of the elastic film        stretchable structure corresponds to a width direction, and    -   a region including the elastic film stretchable structure has        the non-stretchable region and the stretchable region.

(Operational Advantage)

Particularly in each of the underpants-type disposable diapers among theabsorbent articles, the stretchable region is large, and there are a lotof modes used in place of underwear. Thus, a display such as a patternis applied in many cases, and appearance is important. To provide such adisplay, conventionally, it has been common to interpose a sheet onwhich an indication is printed between an inner body and an outer bodyor inside the outer body. However, according to the invention, it ispossible to apply a display having an excellent appearance whileomitting such a printed sheet.

The absorbent article, wherein

-   -   the outer body in at least one of the front body and the back        body includes a torso intermediate region defined as a        front-back direction range between a waist end portion region        and the absorber, and the elastic film stretchable structure is        provided across a width direction range corresponding to the        range between both the side seal portions at least in the torso        intermediate region such that the stretching and contracting        direction thereof corresponds to the width direction, and    -   the torso intermediate region is set to include in an        intermediate portion in the width direction, the non-stretchable        region having the display portion, and the stretchable region in        a width direction range corresponding to a range between the        non-stretchable region and the side seal portion.

(Operational Advantage)

The torso intermediate region is a region not having the absorber, andis soft unlike a region having elasticity such as a region having theabsorber. Thus, the display portion is easily affected by contraction ofthe stretchable region. Therefore, the invention particularly has atechnical meaning when the display portion is provided in the torsointermediate region.

The absorbent article, wherein

-   -   the torso region of the outer body included at least in one of        the front body and the back body includes an absorber region        overlapping the absorber, and the elastic film stretchable        structure disposed across a whole of the width direction at        least of a region from the torso intermediate region to the        absorber region such that the stretching and contracting        direction of the elastic film stretchable structure corresponds        to a width direction, and    -   the region from the torso intermediate region to the absorber        region is set to have the non-stretchable region having the        display portion in an intermediate portion in the width        direction thereof, and the stretchable region at a width        direction range corresponding to a range between the        non-stretchable region and the side seal portion.

(Operational Advantage)

It is unnecessary to impart elasticity to a portion of the outer body ofthe underpants-type disposable diaper which is overlapping the absorbereven though the elastic film is desirably disposed on the portion due toa manufacturing reason. Therefore, it is preferable to form thenon-stretchable region having the display portion, including the portionoverlapping the absorber.

The absorbent article, wherein the elastic film stretchable structure isextended to the waist end portion region, and another stretchablestructure stretchable in a width direction is not provided at the frontand back of the non-stretchable region.

(Operational Advantage)

When the elastic film stretchable structure is extended to the waist endportion region, and another stretchable structure stretchable in a widthdirection is not included as described above, it is possible to omit theconventional elongated waist end portion elastic member which has beenconventionally provided in the waist end portion region, etc., and aninfluence of contraction of the stretchable region on thenon-stretchable region is completely prevented, which is preferable.

The absorbent article, wherein a whole width direction rangecorresponding to a range between the both side seal portions in thewaist end portion region is set to the stretchable region in which anelongated waist end portion elastic member is fixed in a stretched statealong the width direction.

(Operational Advantage)

It is possible to provide a stretchable structure according to aconventional elongated elastically stretchable member without providingthe elastic film stretchable structure in the waist end portion regionas necessary in a case in which tightening of the waist end portionregion is insufficient even with the elastic film stretchable structureused in the waist end portion region, etc.

The absorbent article, wherein

-   -   in the waist end portion region, a width direction range        corresponding to the stretchable region in a region having the        elastic film stretchable structure is set to a stretchable        region in which an elongated waist end portion elastic member is        fixed in a stretched state along the width direction, and    -   in the waist end portion region, a width direction range        corresponding at least to the display portion is set to a        non-stretchable region or a weak stretchable region in which an        elongation at an elastic limit is smaller than that of the        stretchable region in the waist end portion region.

(Operational Advantage)

It is possible to provide a stretchable structure according to aconventional elongated elastically stretchable member without providingthe elastic film stretchable structure in the waist end portion regionas necessary in a case in which tightening of the waist end portionregion is insufficient even with the elastic film stretchable structureused in the waist end portion region, etc. However, in this case, whenthe display portion is provided near the waist end portion region, eventhough the display portion is located in the middle part in thedirection orthogonal to the stretching and contracting direction of thenon-stretchable region, the display portion is likely to be affected bystretching and contraction of the waist end portion region. Therefore,when the stretchable structure according to the elongated elasticallystretchable member is provided, it is also preferable that at least thewidth direction range corresponding to the display portion is set to thenon-stretchable region or the weak stretchable region as describedabove.

The absorbent article, wherein the non-stretchable region is set to haveany one of

-   -   (a) a shape in which a width becomes smaller continuously or        stepwise as progressing toward a waist opening side from a        crotch side,    -   (b) a shape in which the width becomes larger continuously or        stepwise as progressing toward the waist opening side from the        crotch side, and    -   (c) a shape in which the width becomes once larger and after        that becomes smaller continuously or stepwise as progressing        toward the waist opening side from the crotch side.

(Operational Advantage)

When the shape of the non-stretchable region is set to theabove-described shape, the outer body can have a shape with high fittingproperty with respect to a body surface, which is preferable.

The absorbent article, wherein the non-stretchable region has a shapebranched into a plurality of parts as progressing toward a waist openingside from a crotch side, and the stretchable region is provided betweenthe two adjacent branched parts of the non-stretchable region.

(Operational Advantage)

When the shape of the non-stretchable region is set to such a branchedshape, it is possible to provide the display portion based on thenon-stretchable region while preventing the outer body from hardening.

Advantageous Effects of Invention

As described above, according to the invention, there is an advantage inthat an excellent non-stretchable region may be formed in an elasticfilm stretchable structure, etc.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a plan view (internal surface side) of an underpants-typedisposable diaper in the spread state.

FIG. 2 is a plan view (external surface side) of the underpants-typedisposable diaper in the spread state.

FIG. 3 is a plan view illustrating only a main part of theunderpants-type disposable diaper in the spread state.

FIG. 4A is a C-C cross-sectional view of FIG. 1 and FIG. 42 , and FIG.4B is an E-E cross-sectional view of FIG. 1 and FIG. 42 .

FIG. 5 is an A-A cross-sectional view of FIG. 1 .

FIG. 6 is a B-B cross-sectional view of FIG. 1 .

FIG. 7A is a plan view of a main part of a stretchable region, FIG. 7Bis a D-D cross-sectional view of FIG. 7A, FIG. 7C is a cross-sectionalview in a worn state, and FIG. 7D is a cross-sectional view in a naturallength state.

FIG. 8A is a microscope photograph from a plane direction, FIG. 8B is ahigh-magnification microscope photograph from the plane direction, andFIG. 8C is a high-magnification microscope photograph from an obliquedirection in a stretchable region of a sample.

FIG. 9A is a plan view of a main part of the stretchable region, FIG. 9Bis a D-D cross-sectional view of FIG. 9A, FIG. 9C is a cross-sectionalview in the worn state, and FIG. 9D is a cross-sectional view in thenatural length state.

FIG. 10A is a microscope photograph from the plane direction, FIG. 10Bis a high-magnification microscope photograph from the plane direction,and FIG. 10C is a high-magnification microscope photograph from theoblique direction in the stretchable region of the sample.

FIG. 11A is a plan view of a main part of a non-stretchable region, FIG.11B is a D-D cross-sectional view of FIG. 11A, FIG. 11C is across-sectional view in the worn state, and FIG. 11D is across-sectional view in the natural length state.

FIG. 12 is a photograph of the non-stretchable region of the sample.

FIG. 13A and FIG. 13B are plan views of a main part of thenon-stretchable region.

FIG. 14A and FIG. 14B are plan views of a main part of thenon-stretchable region.

FIG. 15 is a plan view (external surface side) of the underpants-typedisposable diaper in the spread state.

FIG. 16A is a C-C cross-sectional view of FIG. 15 and FIG. 22 , and FIG.16B is an E-E cross-sectional view of FIG. 15 and FIG. 22 .

FIG. 17A, FIG. 17B and FIG. 17C are cross-sectional views, eachschematically illustrating a cross section of a main part of an outerbody stretched to some extent.

FIG. 18A, FIG. 18B and FIG. 18C are cross-sectional views, eachschematically illustrating a cross section of a main part of an outerbody stretched to some extent.

FIG. 19A is a plan photograph of a sheet bond portion formed in a firstwelding mode, and FIG. 19B is a plan photograph of the sheet bondportion formed in a third welding mode.

FIG. 20 is a schematic view of an ultrasonic sealing device.

FIG. 21A, FIG. 21B, FIG. 21C, FIG. 21D and FIG. 21E are plan viewsillustrating various arrangement examples of the sheet bond portion.

FIG. 22 is a plan view (internal surface side) of the underpants-typedisposable diaper in a completely spread state.

FIG. 23 is a plan view (external surface side) of the underpants-typedisposable diaper in the completely spread state.

FIG. 24A, FIG. 24B and FIG. 24C are cross-sectional views, eachschematically illustrating a cross section of a main part of the outerbody stretched to some extent in a width direction.

FIG. 25A is a partially fractured plan view illustrating a main part ofthe outer body in the completely spread state before cutting an elasticfilm, and FIG. 25B is a partially fractured plan view illustrating themain part of the outer body in the completely spread state after cuttingthe elastic film.

FIG. 26A is a partially fractured plan view illustrating a main part ofthe outer body in the completely spread state before cutting the elasticfilm, and FIG. 26B is a partially fractured plan view illustrating themain part of the outer body in the completely spread state afterpartially cutting the elastic film.

FIG. 27A is a partially fractured plan view illustrating a main part ofthe outer body in the completely spread state, and FIG. 27B is across-sectional view of a main part after cutting the elastic film.

FIG. 28 is a plan view (external surface side) of the underpants-typedisposable diaper in the fully stretched state.

FIG. 29 is a photograph in a natural length state of a sample of anembodiment.

FIG. 30 is a photograph in a stretched state of the sample of theembodiment.

FIG. 31 is an enlarged photograph of a joint portion.

FIG. 32 is an enlarged photograph of the joint portion in a state inwhich a first sheet layer and a second sheet layer are peeled off.

FIG. 33 is a schematic view illustrating a manufacturing flow of theunderpants-type disposable diaper.

FIG. 34 is a schematic view of an outer body assembly process.

FIG. 35 is a schematic plan view of a main part of the outer body in thecompletely spread state.

FIG. 36A and FIG. 36B are enlarged plan views of a main part, eachillustrating a pattern of joint portions.

FIG. 37A and FIG. 37B are enlarged plan views of a main part, eachillustrating a pattern of joint portions.

FIG. 38 is a plan view (external surface side) of the underpants-typedisposable diaper in the completely spread state.

FIG. 39A, FIG. 39B, FIG. 39C are enlarged plan views of a main part,each illustrating a pattern of joint portions.

FIG. 40 is a photograph in a natural length state of a sample of anembodiment.

FIG. 41 is a photograph in a stretched state of the sample of theembodiment.

FIG. 42 is a plan view (internal surface side) of the underpants-typedisposable diaper in the completely spread state.

FIG. 43 is a plan view (external surface side) of the underpants-typedisposable diaper in the completely spread state.

FIG. 44A, FIG. 44B and FIG. 44C are cross-sectional views, eachschematically illustrating a cross section of a main part of an outerbody stretched to some extent in the width direction.

FIG. 45A and FIG. 45B are schematic front views for description of anoperation.

FIG. 46A, FIG. 46B, FIG. 46C and FIG. 46D are schematic views, eachillustrating a method of forming sheet bond portions.

FIG. 47A, FIG. 47B, FIG. 47C and FIG. 47D are plan views, eachillustrating a pattern example of sheet bond portions around a displayportion.

FIG. 48A, FIG. 48B, FIG. 48C, FIG. 48D, and FIG. 48E are plan views,each illustrating a pattern example of the sheet bond portions aroundthe display portion.

FIG. 49A and FIG. 49B are plan views, each illustrating a patternexample of the sheet bond portions.

FIG. 50 is a plan view (external surface side) of the underpants-typedisposable diaper in the completely spread state.

FIG. 51A, FIG. 51B, FIG. 51C, FIG. 51D and FIG. 51E are front viewsschematically illustrating various modes of the underpants-typedisposable diaper.

FIGS. 52A and 52B are front views and FIG. 52C is a back viewschematically illustrating various modes of the underpants-typedisposable diaper.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the invention will be described withreference to accompanying drawings. A dotted portion in across-sectional view indicates joining means such as a hot-meltadhesive.

<With Regard to Common Matters>

FIG. 1 to FIG. 6 illustrate an underpants-type disposable diaper. Thisunderpants-type disposable diaper (hereinafter also simply referred toas a diaper) has an outer body 20 included in a front body F and a backbody B as one unit, an inner body 10 that is fixed to the internalsurface of the outer body 20 as one unit. Further, in the inner body 10,an absorber 13 is interposed between a liquid pervious top sheet 11 anda liquid impervious sheet 12. In manufacturing, after a back surface ofthe inner body 10 is joined to the internal surface side (upper surface)of the outer body 20 using joining means such as a hot-melt adhesive,the inner body 10 and the outer body 20 are folded at a center in afront-back direction (vertical direction) corresponding to a boundarybetween the front body F and the back body B, and both side portionsthereof are joined to each other by heat sealing, a hot-melt adhesive,etc. to form side seal portions 21, thereby obtaining an underpants-typedisposable diaper in which a waist opening and a pair of right and leftleg openings are formed.

(Exemplary Structure of Inner Body)

With reference to FIGS. 4 to 6 , the inner body 10 includes a top sheet11 composed of, for example, non-woven fabric, a liquid-impermeablesheet 12 composed of, for example, polyethylene, and an absorber 13between the top sheet 11 and the liquid-impermeable sheet 12. The innerbody 10 is configured to absorb and retain excretory fluid passingthrough the top sheet 11. The inner body 10 may have any planar shapeand typically has a substantially rectangular shape as shown in thedrawing.

The top sheet 11 that covers a front surface side (to come into contactwith the skin) of the absorber 13 is preferably composed of perforatedor imperforate nonwoven fabric or a porous plastic sheet. Examples ofthe raw fibers of the nonwoven fabric include synthetic fibers, such asolefin fibers, e.g., polyethylene and polypropylene, polyester fibers,and polyamide fibers; recycled fibers, such as rayon and cupra; andnatural fibers, such as cotton. The nonwoven fabric can be produced byany process, for example, spun lacing, spun bonding, thermal bonding,melt blowing, or needle punching. Among these processes, preferred arespun lacing in view of flexibility and drape characteristics and thermalbonding in view of bulky soft products. A large number of through holesformed in the top sheet 11 facilitates absorption of urine and achievesdry touch characteristics. The top sheet 11 extends around the sideedges of the absorber 13 and extends to the back surface side of theabsorber 13.

The liquid-impermeable sheet 12, covering the back surface side (not incontact with skin) of the absorber 13 is composed of a liquid-imperviousplastic sheet, for example, polyethylene sheet or polypropylene sheet.Recently, permeable films have been preferably used in view ofpreventing stuffiness. This water-block permeable sheet is amicro-porous sheet prepared through melt-kneading an olefin resin, forexample, polyethylene resin or polypropylene resin, and inorganicfiller, forming a sheet with the kneaded materials, and then uniaxiallyor biaxially elongating the sheet.

The absorber 13 may be composed of a well-known basic component, such asan accumulated body of pulp fibers, an assembly of filaments, composedof, for example, cellulose acetate, or non-woven fabric, and theabsorber 13 may include as necessary high-absorbent polymer mixed orfixed to the basic component. The absorber 13 may be wrapped with aliquid-permeable and liquid-retainable package sheet 14, such as a crepesheet, to retain the shape and polymers, as required.

The absorber 13 has a substantially hourglass shape having a narrowportion 13N with a width narrower than those of the front and back endportions of the absorber 13, at a crotch portion. Alternatively, theabsorber 13 may have any other shape, for example, a rectangular shape,as appropriate. The size of the narrow portion 13N may be appropriatelydetermined. The narrow portion 13N may have a length of approximately 20to 50% of the entire length of the diaper along the front-backdirection, and a width, at the narrowest region, of approximately 40 to60% of the entire width of the absorber 13. If the inner body 10 has asubstantially rectangular planar shape in the case of the absorber withsuch a narrower part 13N, the inner body 10 has portions free of theabsorber 13 according to the narrower part 13N of the absorber 13.

Three-dimensional gathers BS, which are configured to fit around thelegs, are formed on both side portions of the inner body 10. Withreference to FIGS. 5 and 6 , the three-dimensional gathers BS are eachcomposed of a gather non-woven fabric 15 folded into a duplicate sheetconsisting of a fixed section fixed to the side portion of the backsurface of the inner body, a main section extending from the fixedsection around a side portion of the inner body to the side portion ofthe front surface of the inner body, lying down sections formed byfixing the front end portion and back end portion of the main section ina lying down state to the side portion of the front surface of the innerbody, and a free section formed in an un-fixed state between both thelying down sections.

Elongated gather elastic members 16 are disposed in the tip portion ofthe free sections of the duplicate sheet. As illustrated by the chaindouble-dashed line in FIG. 5 , part of the non-woven fabric protrudingfrom a side edge of the absorber is erected by elastic stretching forceof the gather elastic members 16 to form a three-dimensional gather BSin a completed product.

The liquid impervious sheet 12 is folded back to the back surface sidetogether with the top sheet 11 at both sides of the absorber 13 in thewidth direction. The liquid-impervious back surface sheet 12 ispreferably opaque to block transmission of brown color of stool andurine. Preferred examples of the opacifying agent compounded in theplastic film include colorant or filler, such as calcium carbonate,titanium oxide, zinc oxide, white carbon, clay, talc, and bariumsulfate.

The gather elastic member 16 may be composed of commodity materials, forexample, styrene rubber, olefin rubber, urethane rubber, ester rubber,polyurethanes, polyethylene, polystyrene, styrene-butadiene, silicones,and polyester. The gather elastic members 16 preferably have a finenessof 925 dtex or less and are disposed under a tension of 150% to 350% atan interval of 7.0 mm or less to be hidden from outside view. The gatherelastic member 16 may have a string shape shown in the drawing or a tapeshape with an appropriate width.

Like the top sheet 11, the gather nonwoven fabric 15 may be composed ofraw fibers including synthetic fibers, such as olefin fibers of, forexample, polyethylene fibers or polypropylene fibers; polyester fibersand amide fibers; recycled fibers of, for example, rayon and cupra; andnatural fibers such as cotton. The gather nonwoven fabric may beprepared by any appropriate process, for example, spun bonding, thermalbonding, melt blowing, or needle punching. In particular, the basisweight should be reduced for production of a nonwoven fabric that canprevent stuffiness and has high air permeability. The gather nonwovenfabric 15 is preferably a water-repellent nonwoven fabric coated with awater repellent agent, for example, a silicone-based agent, aparaffin-metallic agent, or an alkyl chromic chloride agent to preventpenetration of urine and the like, to prevent diaper rash, and toenhance feeling to skin (dryness).

As illustrated in FIG. 3 , the back surface of the inner body 10 isfixed to the internal surface of the outer body 20 by, for example, ahot-melt adhesive in an internal and external fixed region 10B (shadedarea). The internal and external fixed region 10B extends over with awidth from a side portion 17 free of the absorber at one side to anotherside portion 17 free of the absorber at the other side at the both frontand back sides of the side portions 17. Side edges of the internal andexternal fixed region 10B are preferably positioned at lateral sides ofmiddle of the side portions 17 free of the absorber in the widthdirection. In particular, the internal and external fixed region 10B ispreferably fixed to the substantially whole inner body 10 in the widthdirection and fixed to the substantially whole outer body 20 in thefront-back direction.

(Front and Back Cover Sheets)

With reference to FIG. 1 and FIG. 4 , front and back cover sheets 50, 60may be provided to cover the front and back end portions of the innerbody 10 attached to the internal surface of the outer body 20 to preventleakage from the front and rear edges of the inner body 10. In moredetail, the front cover sheet 50 extends over the entire width of thefront body F on the internal surface of the front body F from theinternal surface of the folded part 20C at the waist side end of thefront body F to a position overlapping with the front end portion of theinner body 10. The back cover sheet 60 extends on the internal surfaceof the back body Ba over the entire width, and extends over the entirewidth of the back body B from the internal surface of the folded part20C at the waist side end of the back body B to a position overlappingwith the back end portion of the inner body 10, in the embodimentillustrated in the drawings. Minor non-bonded regions are provided overthe entire width (or only at the central portion) at side edge portionsof the front and back cover sheets 50 and 60 at the crotch portion-side.The front and back cover sheets 50 and 60 having such non-bonded regionscan prevent leakage of the adhesive and function as barriers againstleakage when slightly suspended from the top sheet.

As shown in the embodiment illustrated in the drawings, the front andback cover sheets 50, 60 as separate components advantageously enlargethe range of choice of material, but disadvantageously needs additionalmaterials and manufacturing processes. Thus, the folded part 20C formedby folding back the outer body 20 toward the inner surface side of thediaper are respectively extended to portions overlapping with the innerbody 10, so as to have the same function as that of the cover sheets 50,60.

First Mode

First, a first mode will be described based on FIG. 1 to FIG. 21 . Theouter body 20 is extended to a lateral side of the side edge of theabsorber 13. To this extent, referring to the outer body 20, as in theillustrated mode, a side edge of the outer body 20 may be positioned ata central side of a side edge of the inner body 10 in the widthdirection or at an outer side thereof in the width direction in thecrotch portion. In addition, the outer body 20 has a torso region Tcorresponding to a front-back direction range of each side seal portion21, and an intermediate region L corresponding to a front-back directionrange between the torso region T of the front body F and the torsoregion T of the back body B. Further, in the outer body 20 of theillustrated mode, except for the middle of the intermediate region L inthe front-back direction, an elastic film 30 is stacked between a firstsheet layer 20A and a second sheet layer 20B as illustrated in FIG. 2and FIG. 4 to FIG. 6 , and the first sheet layer 20A and the secondsheet layer 20B have an elastic film stretchable structure 20X, astretching and contracting direction of which corresponds to the widthdirection, joined via through holes 31 penetrating the elastic film 30at a large number of sheet bond portions 40 arranged at intervals asillustrated in FIG. 7 . A planar shape of the outer body 20 is formedincluding concave leg lines 29 such that both side edges of theintermediate region L in the width direction form the leg openings, andcorresponds to a pseudo-hourglass shape as a whole. The outer body 20may be divided into two front and back parts, and the both parts may beseparated from each other in the front-back direction in the crotchportion.

The modes illustrated in FIG. 1 and FIG. 2 correspond to a mode in whichthe elastic film stretchable structure 20X extends to the waist endportion region 23. However, when the elastic film stretchable structure20X is used in the waist end portion region 23, tightening of the waistend portion region 23 is insufficient. It is possible to provide astretchable structure according to a conventional elongated waist endportion elastic member 24 as necessary without providing the elasticfilm stretchable structure 20X in the waist end portion region 23 asillustrated in FIG. 15 and FIG. 16 . The waist end portion elasticmembers 24 correspond to elongated elastic members such as a pluralityof rubber threads disposed at intervals in the front-back direction, andapply a stretching force to tighten around the waist of the body. Thewaist end portion elastic members 24 are not disposed substantially in abundle with a close spacing, and three or more, preferably five or moremembers are disposed at intervals of about 3 to 8 mm to form apredetermined stretchable zone. A stretch rate of the waist end portionelastic member 24 in fixing may be appropriately determined. However,the stretch rate may be set to about 230 to 320% in the case of normaladult use. Rubber threads are used as the waist end portion elasticmembers 24 in an illustrated example. However, for example, anotherelongated elastic member such as flat rubber may be used.

As another mode, although not illustrated, the elastic film stretchablestructure 20X may not be provided in the intermediate region L betweenthe torso region T of the front body F and the torso region T of theback body B, the stretchable structure 20X may be continuously providedin the front-back direction from the inside of the torso region T of thefront body F to the inside of the torso region T of the back body Bthrough the intermediate region L, or the elastic film stretchablestructure 20X may be provided only in any one of the front body F andthe back body B.

A shape of each of the sheet bond portions 40 and the through holes 31in a natural length state may be appropriately determined. However, itis possible to adopt an arbitrary shape such as a perfect circle (seeFIG. 7 and FIG. 8 ), an ellipse, a polygon such as a triangle, arectangle (see FIG. 9 to FIG. 12 ), a rhombus (see FIG. 13B), etc., aconvex lens shape (see FIG. 13A), a concave lens shape (see FIG. 14A), astar shape, a cloud shape, etc. The dimensions of each of the sheet bondportions are not particularly restricted. However, a maximum length 40 xis preferably set to 0.5 to 3.0 mm, particularly 0.7 to 1.1 mm, and amaximum width is preferably set to 0.1 to 3.0 mm, particularly 0.1 to1.1 mm in a case of a shape which is long in a direction orthogonal tothe stretching and contracting direction.

A size of each of the sheet bond portions 40 may be appropriatelydetermined. However, when the size is excessively large, an influence ofhardness of the sheet bond portions 40 on a sense of touch increases.When the size is excessively small, a joining area is small, andmaterials may not be sufficiently attached to each other. Thus, ingeneral, an area of each of the sheet bond portions 40 is preferably setto about 0.14 to 3.5 mm². An area of an opening of each of the throughholes 31 may be greater than or equal to that of each of the sheet bondportions since the sheet bond portions are formed via the through holes31. However, the area is preferably set to about 1 to 1.5 times the areaof each of the sheet bond portions. The area of the opening of eachthrough hole 31 refers to a value in a natural length state in a statethat the elastic film 30, the first sheet layer 20A, and the secondsheet layer 20B are provided in one unit, rather than a state of theelastic film 30 alone, and refers to a minimum value in a case in whichthe area of the opening of each through hole 31 is not uniform in athickness direction such as a case in which the area is differentbetween a front side and a back side of the elastic film 30.

A planar array of the sheet bond portions 40 and the through holes 31may be appropriately determined. However, it is preferable to adopt aplanar array in which the sheet bond portions 40 and the through holes31 are regularly repeated. In addition to the planar array in which thesheet bond portions 40 and the through holes 31 are regularly repeatedsuch as an oblique lattice shape illustrated in FIG. 21A, a hexagonallattice shape illustrated in FIG. 21B (these shapes are also referred toas a staggered shape), a square lattice shape illustrated in FIG. 21C, arectangular lattice shape illustrated in FIG. 21D, a parallel bodylattice shape illustrated in FIG. 21E (a mode in which two groups areprovided such that a large number of parallel oblique row groupsintersect each other as illustrated in the figure), etc. (including amode in which these shapes are inclined at an angle less than 90 degreeswith respect to the stretching and contracting direction), it ispossible to adopt a planar array in which a group of the sheet bondportions 40 (arrangement of a group unit may be regular or irregular,and a pattern, a letter shape, etc. may be used) is regularly repeated.

In the sheet bond portions 40, the first sheet layer 20A and the secondsheet layer 20B are joined via the through holes 31 formed in theelastic film 30. In this case, it is preferable that the first sheetlayer 20A is not and the second sheet layer 20B is not joined to theelastic film 30 in a portion other than at least between the first sheetlayer 20A and the second sheet layer 20B in the sheet bond portions 40.

Joining means for the first sheet layer 20A and the second sheet layer20B in the sheet bond portions 40 is not particularly restricted. Forexample, the first sheet layer 20A and the second sheet layer 20B in thesheet bond portions 40 may be joined using a hot-melt adhesive orjoining means based on material welding such as heat sealing, ultrasonicsealing, etc.

As a mode in which the sheet bond portions 40 are formed by materialwelding, it is possible to adopt any one of a first welding mode (seeFIG. 17A) in which the first sheet layer 20A and the second sheet layer20B are joined only by a melted and solidified material 20 mcorresponding to a most part or a part of at least one of the firstsheet layer 20A and the second sheet layer 20B in the sheet bondportions 40, a second welding mode (see FIG. 17B) in which the firstsheet layer 20A and the second sheet layer 20B are joined only by amelted and solidified material 30 m corresponding to a whole, a mostpart, or a part of the elastic film 30 in the sheet bond portions 40,and a third welding mode (see FIG. 17C) obtained by combining thesewelding modes, and it is preferable to adopt the second and thirdwelding modes. A particularly preferable mode is a mode in which thefirst sheet layer 20A and the second sheet layer 20B are joined by themelted and solidified material 20 m corresponding to a part the firstsheet layer 20A and the second sheet layer 20B and the melted andsolidified material 30 m corresponding to a whole or a most part of theelastic film 30 in the sheet bond portions 40. While the melted andsolidified material 30 m of the elastic film 30 appearing in white isseen in the melted material 20 m with fibers of the first sheet layer20A or the second sheet layer 20B appearing in black in the thirdwelding mode illustrated in FIG. 19B, the melted and solidified materialof the elastic film is not seen in the melted and solidified material 20m of the first sheet layer 20A or the second sheet layer 20B in thefirst welding mode illustrated in FIG. 19A (a while part corresponds toa boundary of the melted and solidified material 20 m with fibers andscattered reflection of the melted and solidified material 20 m) withfibers.

When the first sheet layer 20A and the second sheet layer 20B are bondedusing the melted and solidified material 20 m corresponding to a mostpart or a part of at least one of the first sheet layer 20A and thesecond sheet layer 20B as an adhesive as in a first adhesive mode or athird adhesive mode, it is preferable that a part of the first sheetlayer 20A and the second sheet layer 20B does not melt since the sheetbond portions 40 are not hardened. When the first sheet layer 20A andthe second sheet layer 20B correspond to a nonwoven fabric, a case inwhich a part of the first sheet layer 20A and the second sheet layer 20Bdoes not melt includes a mode in which a core (including a centralportion of a single component fiber in addition to a core in a conjugatefiber) remains for all fibers of the sheet bond portions 40 and asurrounding portion (including a portion on a surface layer side of asingle component fiber in addition to a sheath in a conjugate fiber)melts, or a mode in which some fibers do not melt while all remainingfibers melt or a core remains while a surrounding portion melts.

Peeling strength becomes high when the first sheet layer 20A and thesecond sheet layer 20B are bonded using the melted and solidifiedmaterial 30 m of the elastic film 30 as an adhesive as in the secondwelding mode and the third welding mode. In the second welding mode,under the condition that a melting point of at least one of the firstsheet layer 20A and the second sheet layer 20B is higher than a meltingpoint of the elastic film 30 and a heating temperature at the time offorming the sheet bond portions 40, the elastic film 30 may beinterposed between the first sheet layer 20A and the second sheet layer20B, a part corresponding to the sheet bond portions 40 may be pressedand heated, and only the elastic film 30 may be melted, therebyperforming manufacture. Meanwhile, in the third welding mode, under thecondition that a melting point of at least one of the first sheet layer20A and the second sheet layer 20B is higher than the melting point ofthe elastic film 30, the elastic film 30 may be interposed between thefirst sheet layer 20A and the second sheet layer 20B, the partcorresponding to the sheet bond portions 40 may be pressed and heated,and at least one of the first sheet layer 20A and the second sheet layer20B and the elastic film 30 may be melted, thereby performingmanufacture. From this point of view, the melting point of the elasticfilm 30 is preferably about 80 to 145° C., melting points of the firstsheet layer 20A and the second sheet layer 20B are preferably about 85to 190° C., particularly, 150 to 190° C., and a difference between themelting points of the first sheet layer 20A and the second sheet layer20B and the melting point of the elastic film 30 is preferably about 60to 90° C. In addition, the heating temperature is preferably set to 100to 150° C.

In the second welding mode and the third welding mode, when the firstsheet layer 20A and the second sheet layer 20B are nonwoven fabric, themelted and solidified material 30 m of the elastic film 30 mayinfiltrate among fibers over the whole thickness direction of the firstsheet layer 20A and the second sheet layer 20B of the sheet bondportions 40 as illustrated in FIG. 18C. However, flexibility of thesheet bond portions 40 becomes high in a mode in which the melted andsolidified material 30 m infiltrates among fibers in the thicknessdirection halfway as illustrated in FIGS. 17B, 17C, and FIG. 18A, or amode in which the melted and solidified material 30 m hardly infiltratesamong the fibers of the first sheet layer 20A and the second sheet layer20B as illustrated in FIG. 18B.

FIG. 20 illustrates an example of an ultrasonic sealing device suitablefor forming the second welding mode and the third welding mode. In thisultrasonic sealing device, in forming the sheet bond portions 40, thefirst sheet layer 20A, the elastic film 30, and the second sheet layer20B are fed to between an ultrasonic horn 61 and an anvil roll 60 havingprotrusions 60 a formed in a pattern of the sheet bond portions 40 on anexternal surface. In this instance, for example, when a feed speed ofconveyance of the elastic film 30 at an upstream side by a feed driveroll 63 and a nip roll 62 is set to be lower than a speed of conveyanceafter the anvil roll 60 and the ultrasonic horn 61, the elastic film 30is stretched to a predetermined stretch rate in an MD (machinedirection, flow direction) on a path from a nip position by the feeddrive roll 63 and the nip roll 62 to a sealing position by the anvilroll 60 and the ultrasonic horn 61. A stretch rate of the elastic film30 may be set by selecting a speed difference between the anvil roll 60and the feed drive roll 63, and may be set to, for example, about 300%to 500%. Reference symbol 62 denotes the nip roll. The first sheet layer20A, the elastic film 30, and the second sheet layer 20B fed to betweenthe anvil roll 60 and the ultrasonic horn 61 are heated by ultrasonicvibration energy of the ultrasonic horn 61 while being pressed betweenthe protrusions 60 a and the ultrasonic horn 61 in a stacked state inthis order. Further, the through holes 31 are formed in the elastic film30 by melting only the elastic film 30 or melting at least one of thefirst sheet layer 20A and the second sheet layer 20B and the elasticfilm 30. At the same time, the first sheet layer 20A and the secondsheet layer 20B are joined via the through holes 31. Therefore, in thiscase, an area rate of the sheet bond portions 40 may be selected byselecting a size, a shape, a separation interval, an arrangement patternin a roll length direction and a roll circumferential direction, etc. ofthe protrusions 60 a of the anvil roll 60.

Although the reason for formation of the through holes 31 is notnecessarily clear, it is considered that openings are formed by meltingthe elastic film 30 at corresponding sites to the protrusions 60 a ofthe anvil roll 60 so as to be removed from the surroundings. In thisinstance, a portion between the two adjacent through holes 31 arrangedin the stretching and contracting direction in the elastic film 30 iscut at both sides thereof in the stretching and contracting direction bythe through holes 31 as illustrated in FIG. 7A, FIG. 9A, and FIG. 11A,and support at both the side portions in a contraction direction islost. Thus, within an extent that continuity in a direction orthogonalto the contraction direction can be maintained, the closer to thecentral side of a direction orthogonal to the stretching and contractingdirection, the more elastic film 30 contracts to match with the centralside in the stretching and contracting direction so that the throughholes 31 are enlarged in the stretching and contracting direction. Whenthe sheet bond portions 40 are formed in a pattern with a section beingleft in which the elastic film 30 linearly continues along thestretching and contracting direction, as in the stretchable region 80explained after, the elastic film 30 contracts to the natural lengthstate for example by cutting for obtaining individual products, anenlarged portion of each through hole 31 contracts in the stretching andcontracting direction so that a gap cannot be formed between eachthrough hole 31 and each sheet bond portion 40 as illustrated in FIG. 7Aand FIG. 9A. On the other hand, when the sheet bond portions 40 areformed in a pattern without such a section in which the elastic film 30linearly continues along the stretching and contracting direction, as inthe non-stretchable region 70 explained after, even if the elastic film30 is cut for obtaining the individual products, contraction is notsubstantially performed, as illustrated in FIG. 11A. Thus, a large gapis left between each through hole 31 and each sheet bond portion 40.

(Stretchable Region and Non-Stretchable Region)

A region having the elastic film stretchable structure 20X in the outerbody 20 includes the non-stretchable region 70 and the stretchableregion 80 stretchable in the width direction provided at least at oneside of the non-stretchable region 70 in the width direction.Arrangement of the stretchable region 80 and the non-stretchable region70 may be appropriately determined. In the case of the outer body 20 ofthe underpants-type disposable diaper as in the present embodiment, aportion overlapping the absorber 13 is a region that may not bestretched or contracted. Thus, a part or total of the portionoverlapping the absorber 13 (desirably including substantially the wholeinternal and external fixed region 10B) is preferably set to thenon-stretchable region 70 as in the illustrated mode. Thenon-stretchable region 70 may be provided from a region overlapping theabsorber 13 to a region not overlapping the absorber 13 positioned inthe width direction or the front-back direction thereof, and thenon-stretchable region 70 may be provided only in the region notoverlapping the absorber 13.

(Stretchable Region)

The stretchable region 80 has the section 32 in which the elastic film30 linearly continues along the width direction, contracts in the widthdirection by a contraction force of the elastic film 30 while it ispossible that the stretchable region 80 is stretched in the widthdirection. More specifically, the whole elastic film stretchablestructure 20X including both the stretchable region 80 and thenon-stretchable region 70 is formed by joining the first sheet layer 20Aand the second sheet layer 20B via the through holes 31 of the elasticfilm 30 to form a large number of sheet bond portions 40 arranged atintervals in the width direction and the front-back direction orthogonalthereto (the direction orthogonal to the stretching and contractingdirection) while the elastic film 30 is stretched in the widthdirection. Further, in the stretchable region 80, the through holes 31may be disposed to have the section in which the elastic film 30linearly continues along the width direction, thereby impartingelasticity.

In the stretchable region 80, as illustrated in FIG. 7D and FIG. 9D,when the elastic film 30 is in the natural length state, the first sheetlayer 20A and the second sheet layer 20B between each pair of adjacentsheet bond portions 40 rise in a direction away from each other, andthus a contraction wrinkle 25 extending in the front-back direction isformed. In a worn state in which the elastic film 30 is stretched to anextent in the width direction, as illustrated in FIG. 7C and FIG. 9C,the contraction wrinkles 25 are still remain although the contractionwrinkles 25 are stretched. In addition, as in the illustrated mode, whenthe first sheet layer 20A is not and the second sheet layer 20B is notjoined to the elastic film 30 in a portion other than at least betweenthe first sheet layer 20A and the second sheet layer 20B in the sheetbond portions 40, as understood from FIG. 7C and FIG. 9D assuming theworn state and FIGS. 7A and 7B and FIGS. 9A and 9B assuming a spreadstate of the first sheet layer 20A and the second sheet layer 20B, a gapis formed between each through hole 31 of the elastic film 30 and eachsheet bond portion 40 and in these states, air permeability is imparteddue to the gap even when a material of the elastic film 30 correspondsto a non-porous film or a sheet. In addition, when the elastic film 30is in the natural length state illustrated in FIG. 7D and FIG. 9D, thethrough holes 31 are narrowed by contraction of the elastic film 30, anda gap is hardly formed between the through hole 31 and the sheet bondportion 40. States of the contraction wrinkle 25 in the worn state andthe natural length state are shown in reference sample photographs ofFIG. 8 and FIG. 10 .

An elongation at an elastic limit of the stretchable region 80 in thewidth direction is desirably set to 200% or more (preferably 265% to295%). The elongation at the elastic limit of the stretchable region 80is substantially determined by the stretch rate of the elastic film 30in the manufacturing. However, the elongation at the elastic limitdecreases due to a factor that inhibits contraction in the widthdirection based thereon. A main inhibition factor corresponds to a ratioof the length 40 x of the sheet bond portions 40 to a unit length in thewidth direction. As this ratio increases, the elongation at the elasticlimit decreases. In general, since the length 40 x of the sheet bondportions 40 correlates with the area rate of the sheet bond portions 40,the elongation at the elastic limit of the stretchable region 80 may beadjusted by the area rate of the sheet bond portions 40.

A stretching stress of the stretchable region 80 may be adjusted mainlyby a sum of widths 32 w of the sections 32 in each of which the elasticfilm 30 linearly continues along the width direction. The width 32 w ofthe section 32 in which the elastic film 30 linearly continues along thewidth direction is equal to an interval 31 d of the through holes 31coming into contact with both side edges of the section 32 in thefront-back direction. The interval 31 d of the adjacent two throughholes 31 is equal to an interval 40 d of the adjacent two sheet bondportions 40 coming into contact with the both side edges of the sectionin which the elastic film 30 linearly continues in the front-backdirection when a length 31 y of each through hole 31 in the front-backdirection is equal to a length 40 y of each sheet bond portion 40 in thefront-back direction (when a scheme of simultaneously forming thethrough holes 31 and the sheet bond portions 40 described above isadopted). Therefore, in this case, the stretching stress of thestretchable region 80 may be adjusted by a ratio of the length 40 y ofthe sheet bond portions 40 to a unit length in the front-back direction.In general, since the length 40 y of the sheet bond portions 40correlates with the area rate of the sheet bond portions 40, thestretching stress of the stretchable region 80 may be adjusted by thearea rate of the sheet bond portions 40. The stretching stress at thetime of stretching to an elastic limit of 50% may be estimated as thestretching stress of the stretchable region 80.

The area rate of the sheet bond portions 40 and the area of each of thesheet bond portions 40 in the stretchable region 80 may be appropriatelydetermined. However, in general, the area rate and the areas arepreferably set within the following ranges.

Area of each of sheet bond portions 40: 0.14 to 3.5 mm² (particularly0.14 to 1.0 mm²)

Area rate of sheet bond portions 40: 1.8 to 19.1% (particularly 1.8 to10.6%)

As described above, the elongation at the elastic limit and thestretching stress of the stretchable region 80 may be adjusted by thearea of each of the sheet bond portions 40. Thus, as illustrated in FIG.15 , it is possible to provide a plurality of regions having differentarea rates of the sheet bond portions 40 in the stretchable region 80,and to change fitness according to sites. In a mode illustrated in FIG.15 , a region 81 extending in an oblique direction along a groin and anedge portion region 82 of the leg opening in the front body F have ahigh area rate of the sheet bond portions 40, and thus have a smallstretching stress when compared to the other regions. Therefore, theregions correspond to a region that flexibility stretches and contracts.In addition, an ilium facing region 83 and the edge portion region 82 ofthe leg opening in the back body B have a high area rate of the sheetbond portions 40, and thus have a small stretching stress when comparedto the other regions. Therefore, the regions correspond to a region thatflexibility stretches and contracts.

(Non-Stretchable Region)

Meanwhile, the non-stretchable region 70 is set to a region not havingthe section in which the elastic film 30 linearly continues along thewidth direction due to the presence of the through holes 31 even throughthe elastic film 30 continues in the width direction. Therefore, eventhough the whole elastic film stretchable structure 20X including boththe stretchable region 80 and the non-stretchable region 70 is formed byjoining the first sheet layer 20A and the second sheet layer 20B via thethrough holes 31 of the elastic film 30 to form the large number ofsheet bond portions 40 at intervals in the width direction and thefront-back direction orthogonal thereto while the elastic film 30 isstretched in the width direction, the elastic film 30 does not linearlycontinue along the width direction in the non-stretchable region 70 asillustrated in FIG. 11 . Thus, the contraction force of the elastic film30 hardly acts on the first sheet layer 20A and the second sheet layer20B, elasticity is almost lost, and an elongation at an elastic limitapproaches 100%. Further, in the non-stretchable region 70, the firstsheet layer 20A and the second sheet layer 20B are joined by the largenumber of sheet bond portions 40 arranged at intervals, and the sheetbond portions 40 are discontinuous. Thus, a decrease in flexibility isprevented. In other words, it is possible to form the stretchable region80 and the non-stretchable region 70 depending on the presence orabsence of a portion in which the elastic film 30 does not linearlycontinue along the width direction. In addition, continuity of theelastic film 30 remains in the non-stretchable region 70. As understoodfrom a sample photograph illustrated in FIG. 12 , since an independentcut piece of the elastic film 30 is not left, and no wrinkle is formed,appearance is extremely excellent, and air permeability in the thicknessdirection by the through holes 31 is ensured. In the non-stretchableregion 70, an elongation at elastic limit in the width direction ispreferably 120% or less (preferably 110% or less, more preferably 100%).

An arrangement pattern of the through holes 31 in the elastic film 30 inthe non-stretchable region 70 may be appropriately determined. However,when staggered arrangement is adopted as illustrated in FIG. 11 to FIG.14 , and a pattern in which a center-to-center interval 31 e of theadjacent two through holes 31 in the front-back direction is shorterthan the length 31 y of each of the through holes 31 in the front-backdirection is adopted, linear continuity in the width direction may bealmost completely eliminated while maintaining continuity of the elasticfilm 30, and appearance is preferable as illustrated in FIG. 15 . Inthis case, it is more preferable that a center-to-center interval 31 fof the adjacent two through holes 31 in the width direction is shorterthan a length 31 x of each of the through holes 31 in the widthdirection.

In general, especially when a stretching stress is in a range of 4 to 12N/35 mm at the time of stretching the elastic film 30 four times in thewidth direction, in a state in which the non-stretchable region 70 isstretched to an elongation at an elastic limit in the width direction,the center-to-center interval 31 e of the adjacent two through holes 31in the front-back direction is preferably in a range of 0.4 to 2.7 mm,and the length 31 y of the through holes 31 in the front-back directionis preferably in a range of 0.5 to 3.0 mm, particularly in a range of0.7 to 1.1 mm. In addition, the center-to-center interval 31 f of theadjacent two through holes 31 in the width direction is preferably 0.5to 2 times, particularly 1 to 1.2 times the length 31 y of the throughholes 31 in the front-back direction, and the length 31 x of the throughholes 31 in the width direction is preferably 1.1 to 1.8 times,particularly 1.1 to 1.4 times the center-to-center interval 31 f of theadjacent two through holes 31 in the width direction. In a state inwhich the non-stretchable region 70 is stretched to an elastic limit inthe width direction (in other words, in a state in which the first sheetlayer 20A and the second sheet layer 20B are completely spread), thecenter-to-center interval 31 f of the adjacent two through holes 31 inthe width direction is equal to a center-to-center interval 40 f of theadjacent two sheet bond portions 40 in the width direction, thecenter-to-center interval 31 e of the adjacent two through holes 31 inthe front-back direction is equal to a center-to-center interval 40 e ofthe adjacent two sheet bond portions 40 in the front-back direction, andthe length 31 y of the through holes 31 in the front-back direction isequal to the length 40 y of the sheet bond portions 40 in the front-backdirection.

In the non-stretchable region 70, in a case in which the first sheetlayer 20A is not and the second sheet layer 20B is not joined to theelastic film 30 in a portion other than between the first sheet layer20A and the second sheet layer 20B in the sheet bond portions 40, and inthe natural length state, a gap is provided so as to contain both sideportions of each of the sheet bond portions 40 in the width direction,which is generated by peripheral edge of the through hole 31 of theelastic film 30 and the sheet bond portion 40 separated from each other,air permeability is imparted at all times due to the gap even when thematerial of the elastic film 30 corresponds to a non-porous film or asheet, and thus the case is preferable. In the case of adopting a schemeof simultaneously forming the through holes 31 and the sheet bondportions 40 described above, this state is naturally obtainedirrespective of a shape of the sheet bond portions 40.

The shape of each of the sheet bond portions 40 and each of the throughholes 31 in the natural length state is not particularly restricted.However, it is desirable to have a small area from a viewpoint offlexibility, and it is desirable to have a shape which is long in thefront-back direction to eliminate linear continuity in the widthdirection of the elastic film 30. Thus, it is preferable to adopt anellipse which is long in the front-back direction, a rectangle (see FIG.11 ), the rhombus (see FIG. 13B, the convex lens shape (see FIG. 13A),and the concave lens shape (see FIG. 14A). However, when corners areacute as in the rhombus, the elastic film 30 is easily fractured. Incontrast, the convex lens shape is preferable since welding of the sheetbond portions 40 is stabilized, and the concave lens shape is preferablein that an area may be further reduced.

It is possible to appropriately determine the area rate of the sheetbond portions 40 and the area of each of the sheet bond portions 40 inthe non-stretchable region. However, in general, ranges below arepreferable since the area of each of the sheet bond portions 40 issmall, the area rate of the sheet bond portions 40 is low, and thus thenon-stretchable region 70 is not hardened.

Area of each of sheet bond portions 40: 0.10 to 0.75 mm² (particularly0.10 to 0.35 mm²)

Area rate of sheet bond portions 40: 4 to 13% (particularly 5 to 10%)

As described above, the elongation at the elastic limit of thenon-stretchable region 70 may be changed by the arrangement pattern ofthe through holes 31, the dimension of each of the through holes 31, andthe center-to-center interval of the adjacent two through holes 31.Therefore, although not illustrated, it is possible to make theelongation at the elastic limit different among a plurality of positionsin the stretchable region 80 or a plurality of non-stretchable regions70. For example, in a preferable mode, an elongation at an elastic limitin the non-stretchable region 70 of the front body F is set to be largerthan an elongation at elastic limit in the non-stretchable region 70 ofthe back body B.

Second Mode

Next, a second mode will be described with reference to FIG. 3 , FIG. 5to FIG. 7 , FIG. 16 , FIG. 21 , and FIG. 22 to FIG. 34 . In the outerbody 20, as illustrated in FIG. 16 , FIG. 5 , and FIG. 6 , the elasticfilm 30 and the elongated elastic member 24 along the width directionare arranged between the first sheet layer 20A and the second sheetlayer 20B, and elasticity in the width direction is imparted. The planarshape of the outer body 20 corresponds to a pseudo-hourglass shape as awhole due to the concave leg lines 29 formed to form leg openings atintermediate both side portions, respectively. The outer body 20 may bedivided into two front and back parts, and the both parts may beseparated from each other in the front-back direction in the crotchportion.

More specifically, in the outer body 20 of the illustrated mode, thewaist end portion elastic member 24 is provided in the waist end portionregion 23 in the torso region T determined as a vertical direction rangeof each side seal portion 21 in which the front body F and the back bodyB are joined. The waist end portion elastic members 24 of theillustrated mode correspond to elongated elastic members such as aplurality of rubber threads disposed at intervals in the verticaldirection, and apply a stretching force to tighten around the waist ofthe body. The waist end portion elastic members 24 are not disposedsubstantially in a bundle with a close spacing, and three or more,preferably five or more members are disposed at intervals of about 3 to8 mm to form a predetermined stretchable zone. A stretch rate of thewaist end portion elastic member 24 in fixing may be appropriatelydetermined. However, the stretch rate may be set to about 230 to 320% inthe case of normal adult use. One or a plurality of belt shaped elasticmembers may be used as the waist end portion elastic member 24.

The rubber threads are used as the waist end portion elastic member 24in an illustrated example. However, for example, a tape shaped elasticmember may be used, and an elastic film described below may be extendedto the waist end portion region 23 instead of using the tape shapedelastic member. The waist end portion elastic member 24 in theillustrated mode is interposed in the folded part 20C formed by foldingback a component of the second sheet layer 20B to the internal surfaceside at a waist opening edge. However, the waist end portion elasticmember 24 may be interposed between a component of the first sheet layer20A and the component of the second sheet layer 20B.

In this embodiment, as illustrated in FIG. 23 , the elastic filmstretchable structures 20X are formed in the torso region T of the frontbody F, the torso region T of the back body B and the intermediateregion L therebetween in the outer body 20. That is, in the stretchablestructure 20X of the outer body 20, the non-stretchable region 70 isformed in the intermediate portion in the width direction, whichincludes parts of the outer body 20 overlapping with the absorber 13(the non-stretchable region 70 may entirely or partly overlap with theabsorber 13 and preferably should contain the substantially entire fixedportion 10B of the inner member) as well as the stretchable regions 80extend to both the side seal portions 21 in the width direction. Theelastic film 30 is, as shown in FIG. 16 and FIGS. 5 to 7 , stackedbetween the first sheet layer 20A and the second sheet layer 20B overthe entire stretchable regions 80 and the non-stretchable region 70.

In the stretchable region 80, while the elastic film 30 is beingstretched in the width direction, the first sheet layer 20A and thesecond sheet layer 20B are joined at a large number of sheet bondportions 40 arranged at intervals in the stretching and contractingdirection and the direction orthogonal thereto (the width direction andthe front-back direction in the underpants-type disposable diaper as inthe illustrated mode) via the through holes 31 formed in the elasticsheet layer 30. In this case, it is desirable that the first sheet layer20A is not and the second sheet layer 20B is not joined to the elasticfilm 30 (except for a melted and solidified material described below).However, joining is allowed. In the stretchable region 80, asillustrated in FIG. 7D, in the natural length state of the elastic film30, the first sheet layer 20A and the second sheet layer 20B betweeneach pair of adjacent sheet bond portions rise in a direction away fromeach other, and thus a contraction wrinkle 25 extending in a directionintersecting the stretching and contracting direction is formed. Asillustrated in FIG. 7C, in a worn state of being stretching to someextent in the width direction, the contraction wrinkle 25 is left eventhough the contraction wrinkle 25 is stretched. In addition, as in theillustrated modes, when the first sheet layer 20A is not and the secondsheet layer 20B is not joined to the elastic film 30 in a portion otherthan at least between the first sheet layer 20A and the second sheetlayer 20B, as understood from FIG. 7C assuming the worn state and FIGS.7A and 7B assuming a completely spread state of the first sheet layer20A and the second sheet layer 20B, in these states, a gap is formedbetween each sheet bond portion 40 and each through hole 31 for thesheet bond portion in the elastic film 30, thus, air permeability isimparted due to the gap even when a material of the elastic film 30corresponds to a non-porous film or a sheet. States of the contractionwrinkle 25 in the worn state and the natural length state are shown insample photographs of FIG. 29 and FIG. 30 . The elongation at theelastic limit of the stretchable region 80 may be adjusted by the arearate of the sheet bond portions 40. In general, the elongation at theelastic limit of the stretchable region 80 in the stretching andcontracting direction is desirably set to 200% or more (preferably 265to 295%).

In the non-stretchable region 70, as illustrated in FIG. 23 , FIG. 25B,and FIG. 27B, the first sheet layer 20A and the second sheet layer 20Bare joined by welding at rows 40L of a plurality of rows of sheet bondportions 40 which extends in a dotted line in the direction intersectingthe stretching and contracting direction and is disposed at intervals inthe stretching and contracting direction. Therefore, even though thefirst sheet layer 20A and the second sheet layer 20B are integrated bywelding in the sheet bond portions 40, the sheet bond portions 40 arediscontinuous, and thus a decrease in flexibility is prevented.Meanwhile, the elastic film 30 is cut along the rows 40L of the sheetbond portions 40, and portions at both sides of cut positions contractas indicated by arrows in the figure and are left at both sides of therows 40L of the sheet bond portions 40 in the stretching and contractingdirection in the natural length state. As a result, the non-stretchableregion 70 corresponds to a region in which elasticity of the elasticfilm 30 is reliably eliminated and the elastic film 30 is discontinuous.Thus, air permeability is excellent. The elongation at the elastic limitin the stretching and contracting direction in the non-stretchableregion 70 may be 130% or less, preferably 120% or less. In particular,according to the invention, the elongation at the elastic limit may beset to 100%. Characteristically, as understood from a comparison of FIG.25A illustrating a state before fracture of perforation 33 and FIG. 25Band FIG. 27B illustrating a state after fracture of the perforation 33,a cut portion of the elastic film 30 is formed by fracture of theperforation 33 formed by melting in the elastic film 30. In other words,since the cut portion resulting from melting is discontinuous, a traceof cutting resulting from melting is discontinuous. Further, appearanceis excellent, and a decrease in flexibility may be prevented. Referencesymbol 34 in FIG. 25B indicates a portion in which the perforation 33 ofthe elastic film 30 is fractured.

The illustrated mode is formed by a manufacturing method describedbelow, and the perforation 33 is formed by the through holes 31 formedby melting the elastic film 30 in a corresponding part using welding ofthe sheet bond portions 40. Thus, positions of the sheet bond portions40 correspond to positions of the through holes 31 of the perforation33, and only the sheet bond portions 40 correspond to the trace ofcutting of the elastic film 30. Without forming the perforation 33 inthe elastic film 30 by welding of the sheet bond portions 40, theperforation 33 may be formed in a separate elastic film 30, and theperforation 33 may be fractured.

In particular, in the non-stretchable region 70 of the illustrated mode,a plurality of rows of the sheet bond portions 40 is provided atintervals in the stretching and contracting direction, cut pieces of theelastic film 30 are left in a natural length state by straddling everyother row of the respective rows of the sheet bond portions 40 in thestretching and contracting direction, and the first sheet layer 20A andthe second sheet layer 20B are joined via the through holes 31 providedin a part of the rows of the sheet bond portions 40 in the cut pieces ofthe elastic film 30 (the through holes 31 of the perforation 33 which isleft without being fractured). Therefore, as illustrated in FIG. 25B andFIG. 27 , a cut piece which is free due to cutting in the elastic film30 and in a natural length state is fixed by joining of the first sheetlayer 20A and the second sheet layer 20B, and thus it is possible toprevent appearance or wearing feeling from being degraded due tomovement of the cut piece. Unlike the illustrated mode, only one row ofthe sheet bond portions 40 may be formed in the middle in the widthdirection, and the elastic film 30 may be cut along the row of the sheetbond portions 40. However, in this case, the elastic film 30 is notfixed in the non-stretchable region 70, and movement is restricted bythe sheet bond portions 40 in the stretchable region 80.

A shape of each of the sheet bond portions 40 and the through holes 31in the natural length state may be set to an arbitrary shape such as aperfect circle, an ellipse, a polygon such as a rectangle (including alinear shape or a rounded corner), a star shape, a cloud shape, etc. Inparticular, when the perforation 33 is formed by melting the elasticfilm 30 in the corresponding site through welding of the sheet bondportions 40 as in the non-stretchable region 70 of the illustrated mode,the shape of the sheet bond portions 40 preferable corresponds to arectangle having a long side along the direction intersecting thestretching and contracting direction such that the perforation 33 iseasily fractured.

A size of each of the sheet bond portions 40 in the stretchable region80 and the non-stretchable region 70 may be appropriately determined.However, when the size is excessively large, an influence of hardness ofthe sheet bond portions 40 on a sense of touch increases. When the sizeis excessively small, a joining area is small, and materials may not besufficiently attached to each other. Thus, in general, an area of eachof the sheet bond portions 40 is preferably set to about 0.14 to 3.5mm². An area of an opening of each of the through holes 31 in thestretchable region 80 may be greater than or equal to that of each ofthe sheet bond portions 40 since the sheet bond portions 40 are formedvia the through holes 31. However, the area is preferably set to about 1to 1.5 times the area of each of the sheet bond portions 40. When theperforation 33 is included in the elastic film in the non-stretchableregion 70 as in the illustrated mode, the area of the opening of each ofthe through holes 31 of the perforation 33 may be set to a similar size.The area of the opening of each of the through holes 31 refers to avalue obtained when the stretchable structure 20X is in a natural lengthstate, and refers to a minimum value in a case in which the area of theopening of each of the through holes 31 is not uniform in a thicknessdirection such as a case in which the area is different between a frontside and a back side of the elastic film 30.

The area of each of the sheet bond portions and the area rate of thesheet bond portions 40 in each region may be appropriately determined.However, an elongation at an elastic limit is affected in thestretchable region 80. Thus, in general, the area and the area rate arepreferably set to within the following ranges.

(Non-Stretchable Region 70)

Area of each of sheet bond portions 40: 0.14 to 3.5 mm² (particularly0.4 to 3.0 mm²)

Area rate of sheet bond portions 40: 0.8 to 18.0% (particularly 1.0 to10.6%)

(Stretchable Region 80)

Area of each of sheet bond portions 40: 0.14 to 3.5 mm² (particularly0.14 to 1.0 mm²)

Area rate of sheet bond portions 40: 1.8 to 22.5% (particularly 1.8 to10.6%)

The area rate of the sheet bond portions 40 may be changed by changingthe number of sheet bond portions 40 per unit area or the area of eachof the sheet bond portions 40. In a former case, the area of each of thesheet bond portions 40 may be the same or different between thenon-stretchable region 70 and the stretchable region 80. In a lattercase, the number of sheet bond portions 40 per unit area may be the sameor different between the non-stretchable region 70 and the stretchableregion 80.

A planar array of the sheet bond portions 40 and the through holes 31 inthe stretchable region 80 may be appropriately determined. However, itis preferable to adopt a planar array in which the sheet bond portions40 and the through holes 31 are regularly repeated. In addition to theplanar array in which the sheet bond portions 40 and the through holes31 are regularly repeated such as an oblique lattice shape illustratedin FIG. 21A, a hexagonal lattice shape illustrated in FIG. 21B (theseshapes are also referred to as a staggered shape), a square latticeshape illustrated in FIG. 21C, a rectangular lattice shape illustratedin FIG. 21D, a parallel body lattice shape illustrated in FIG. 21E (amode in which two groups are provided such that a large number ofparallel oblique row groups intersect each other as illustrated in thefigure), etc. (including a mode in which these shapes are inclined at anangle less than 90 degrees with respect to the stretching andcontracting direction), it is possible to adopt a planar array in whicha group of the sheet bond portions 40 (arrangement of a group unit maybe regular or irregular, and a pattern, a letter shape, etc. may beused) is regularly repeated. An arrangement mode of the sheet bondportions 40 and the through holes 31 may be the same or differentbetween the stretchable region 80 and the non-stretchable region 70.

A planar array of the sheet bond portions 40 in the non-stretchableregion 70 is not restricted as long as the planar array corresponds to apattern of one row extending in a dotted line in the directionintersecting the stretching and contracting direction or a plurality ofrows, each of which is extending in a dotted line in the directionintersecting the stretching and contracting direction, and which aredisposed at intervals in the stretching and contracting direction, thatis, as long as gaps in each of which the first sheet layer 20A and thesecond sheet layer 20B are not joined, are formed between each pair ofadjacent rows of the sheet bond portions 40 each having a dotted lineshape, and the gaps continue in the direction intersecting thestretching and contracting direction.

In addition, dimensions of the perforation 33 for cutting the elasticfilm 30 in the non-stretchable region 70 may be appropriatelydetermined. However, when the elastic film 30 having tensile strengthand tensile elongation described below is used, a length 31 y of thethrough holes 31 in a direction along the perforation 33 (a length of aso-called cut portion) is preferably set to 0.5 to 10 mm, particularlyabout 0.7 to 5 mm, an interval 31 c of the adjacent two through holes 31in the direction along the perforation 33 (a length of a so-called tieportion) is preferably set to 0.3 to 1 mm, particularly about 0.75 to 1mm, a ratio thereof (a so-called cut/tie ratio) is preferably set to 1:2to 10:1, and an interval 31 m of the adjacent two through holes 31 inthe stretching and contracting direction is preferably set to 1 to 20mm, particularly about 3 to 10 mm. When the perforation 33 is formed bythe through holes 31 formed by melting the elastic film 30 in thecorresponding site by welding of the sheet bond portions 40 as in theillustrated mode, the length 31 y of the through holes 31 in thedirection along the perforation 33 is equal to the length 40 y of thesheet bond portions 40 in the same direction, the interval 31 c of theadjacent two through holes 31 in the direction along the perforation 33is equal to the interval 40 c of the adjacent two sheet bond portions 40in the same direction, the interval 31 m of the adjacent two throughholes 31 in the stretching and contracting direction is equal to theinterval 40 c of the adjacent two sheet bond portions 40 in the samedirection, and the sheet bond portions 40 may be formed to satisfy thiscondition of the through holes 31.

When the stretchable structure 20X of the elastic film 30 is formed tobe wider than the non-stretchable region 70 in the directionintersecting the stretching and contracting direction, the elastic film30 may be cut over the whole non-stretchable region 70 in the directionintersecting the stretching and contracting direction, and may not becompletely cut from an end to another end in the direction intersectingthe stretching and contracting direction in the elastic film 30. Forexample, as illustrated in FIG. 23 , in the underpants-type disposablediaper, the non-stretchable region 70 is restricted to a portionoverlapping the absorber 13, and a portion at a waist side thereof isset to the stretchable region 80 over the whole width direction in manycases. However, in such a case, as in the illustrated mode, the elasticfilm 30 may be provided in an integrated manner up to the waist side ofthe portion overlapping the absorber 13, and the elastic film 30 may becut only in the portion overlapping the absorber 13. As illustrated inFIG. 28 , the elastic film 30 may be completely cut from a front end toa back end such that the non-stretchable region 70 continues from an endof the elastic film 30 on the crotch side to an end thereof on the waistside.

Joining means for the first sheet layer 20A and the second sheet layer20B in the sheet bond portions 40 is not particularly restricted. Forexample, the first sheet layer 20A and the second sheet layer 20B in thesheet bond portions 40 may be joined by a hot-melt adhesive, or byjoining means based on material welding such as heat sealing, ultrasonicsealing, etc. When the joining means based on material welding is used,the through holes of the elastic film may be formed by protrusions, andthe first sheet layer 20A and the second sheet layer 20B may be directlyjoined by welding at positions of the through holes as in PatentLiterature 1. However, there is a concern that since the peelingstrength is low, peeling may occur when a strong force is applied. Inaddition, in Patent Literature 1, since the through holes of the elasticfilm are formed by protrusions, the elastic film 30 is not left betweenthe first sheet layer 20A and the second sheet layer 20B as illustratedin FIG. 24B, and there is a concern that protrusion debris (notillustrated) may be movably left around the through holes 31. Inaddition, unlike Patent Literature 1, as illustrated in FIG. 24C,joining the first sheet layer 20A and the second sheet layer 20B throughthe elastic film 30 without forming the through holes in the elasticfilm 30 may be taken into consideration. However, in this case, there isa problem that not only separation strength is low, and but also airpermeability is extremely low since the through holes 31 are notincluded.

Therefore, when the joining means based on material welding is used, itis preferable to adopt a mode in which the first sheet layer 20A and thesecond sheet layer 20B in the sheet bond portions 40 are joined by atleast the melted and solidified material 30 m of the elastic film 30among the first sheet layer 20A and the second sheet layer 20B asillustrated in FIG. 24A. When the first sheet layer 20A and the secondsheet layer 20B are joined using the melted and solidified material 30 mof the elastic film 30 as an adhesive as described above, separationstrength is high, and it is possible to achieve both high airpermeability and high separation strength.

In such a joining structure, for example, when welding is performed in apredetermined pattern of the sheet bond portions 40 in the stretchableregion 80 and the non-stretchable region 70 in a state in which theelastic film 30 is interposed between the first sheet layer 20A and thesecond sheet layer 20B while being stretched in the stretching andcontracting direction at a substantially uniform stretch rate in thedirection orthogonal to the stretching and contracting direction asillustrated in FIG. 33 and FIG. 34 , the elastic film 30 is melted at alarge number of positions to form the through holes 31. At the sametime, manufacture may be simply and efficiently performed using a schemeof joining the first sheet layer 20A and the second sheet layer 20B bysolidification of at least a melted material of the elastic film 30 atpositions of the through holes 31. In the stretchable region 80 and thenon-stretchable region 70 manufactured by this scheme, the shape/area ofeach of the sheet bond portions 40 is substantially equal to theshape/area of each of the through holes 31 in the natural length state.

When this scheme is adopted, a welding process is performed in a weldingpattern corresponding to the row of the sheet bond portions 40 describedabove, that is, a welding pattern of a plurality of rows, each of whichis extended in a dotted line shape in a CD, and which are disposed atintervals in an MD in the non-stretchable region 70. In this case, theelastic film 30 is melted in a welding pattern of extending in a dottedline shape, the through holes 31 are formed in a shape of theperforation 33 as illustrated in FIG. 25A and FIG. 26A, the first sheetlayer 20A and the second sheet layer 20B are joined via the throughholes 31 of the perforation 33 to form the sheet bond portions 40, andthen the perforation 33 is fractured by a tensile force (line tension ofa production line) applied by stretching the elastic film 30. In thisway, as illustrated in FIG. 25B and FIG. 27 , it is possible to form theabove-described non-stretchable region 70 in which the elastic film 30is cut.

In addition, when the perforation 33 is fractured by a tensile forceapplied by stretching the elastic film 30, there is a concern that theperforation 33 of the elastic film 30 may be fractured substantially atthe same time with the welding process, and thus the elastic film 30 maynot be continuously conveyed. Therefore, in a proposed scheme, to formthe sheet bond portions 40 and the through holes 31 illustrated in FIG.26A, a welding process is performed using a pattern having a portion inwhich an interval between the two adjacent welding points in the CDcorresponds to a first interval (equal to an interval 40 c of theadjacent two sheet bond portions 40 in each through hole and an interval31 c of the two adjacent through holes 31), and a portion correspondingto a second interval (equal to an interval 40 d of the adjacent twosheet bond portions 40 and an interval 31 d of the adjacent two throughholes 31) wider than the first interval as a welding pattern of thedotted line. When the welding pattern of the dotted line described aboveis adopted, ties of perforation (tying portions each of which isprovided between the two adjacent through holes 31) formed in theelastic film 30 become ties each having the same length as that of thefirst interval and ties each having the same length as that of thesecond interval. When the perforation 33 is fractured by the tensileforce applied by stretching the elastic film 30, the ties each havingthe same length as that of the first interval are first fractured asillustrated in FIG. 26B, and then the ties each having the same lengthas that of the second interval are fractured as illustrated in FIG. 27A.Accordingly, it is possible to increase time taken from the weldingprocess to fracturing the whole of the perforation 33 of the elasticfilm 30. Therefore, a situation can be prevented in which theperforation 33 of the elastic film 30 is fractured almost at the sametime that the welding process is performed and thus the elastic film 30cannot be continuously conveyed.

FIG. 33 illustrates an example of a method of manufacturing theunderpants-type disposable diaper. This production line corresponds to ahorizontal flow mode in which the width direction of the diaper is theMD (machine direction, line flow direction), and the outer body 20 isformed thereon. After the inner body 10 manufactured on another line isattached to the outer body 20, both side portions of front and backouter bodies 20 are joined by folding at a center in the front-backdirection, and division into individual diapers DP is performed. For thesake of easy understanding, the same name and reference symbol as thoseof a member after manufacture are used for members that are continuousin a manufacturing process.

More specifically, this production line includes an outer body assemblyprocess 301, an inner body attachment process 302, a leg openingpunching process 303, a folding process 304, and a side portionjoining/separation process 305. Among these processes, the outer bodyassembly process 301 is a characteristic process. In more detail, in theouter body assembly process 301, as enlarged and illustrated in FIG. 34, the first sheet layer 20A and the second sheet layer 20B continuing ina belt shape at a predetermined width are fed to sealing devices 60 and61 and such that the first sheet layer 20A and the second sheet layer20B are bonded along a continuing direction thereof, and the elasticfilm 30 continuing in a belt shape at a predetermined width passesthrough a nip roll 90 corresponding to a slower feed speed than speedsof the sealing devices 60 and 61 and are fed to the sealing devices 60and 61 by being interposed between the first sheet layer 20A and thesecond sheet layer 20B in a state of being stretched in the MD due to aspeed difference. In an illustrated mode, one sheet material issegmented into two parts by a slitter 62 to feed the first sheet layer20A as separate front and back parts. However, the sheet material may befed as separate front and back parts, and an integrated front and backsheet material may be fed similarly to the second sheet layer 20Bwithout separating the first sheet layer 20A into front and back parts.Similarly, in the illustrated mode, one elastic film 30 is segmentedinto two parts by the slitter 62 to feed the elastic film 30 as separatefront and back parts. However, the elastic film 30 may be fed asseparate front and back parts, and an integrated front and back elasticfilm 30 may be fed without separating the elastic film 30 into front andback parts.

In the sealing devices 60 and 61, the first sheet layer 20A, the elasticfilm 30 stretched in the MD, and the second sheet layer 20B areinterposed by a seal roll 60 having a large number of pressingprotrusions 60 p arranged in a pattern of the sheet bond portions 40 inthe stretchable region 80 and the non-stretchable region 70 describedabove on an outer circumference surface, and an anvil roll 61 which isdisposed to face the seal roll 60 and has a smooth surface. Further, theelastic film 30 is melted only sites where it is pressed in thethickness direction between the pressing protrusions 60 p and an outercircumference surface of the anvil roll 61 by heating the pressingprotrusions 60 p, thereby forming the through holes 31, and the firstsheet layer 20A and the second sheet layer 20B are bonded by welding atpositions of the through holes 31. A heat sealing device is assumed tobe used as the sealing devices 60 and 61 of the illustrated mode.However, it is possible to use another device such as an ultrasonicsealing device.

In the sealing devices 60 and 61, the outer body 20 in which the sheetbond portions 40 are formed is fractured by a tensile force (linetension of the production line) applied to the perforation 33 of theelastic film 30 by stretching the elastic film 30 at a downstream sideof the sealing devices 60 and 61, and the outer body 20 having thestretchable region 80 and the non-stretchable region 70 in which theelastic film 30 is cut described above is formed. Thereafter, theunderpants-type disposable diaper may be formed by adopting a knownmanufacturing process. In the illustrated mode, the inner body 10manufactured on another line is fed at a predetermined interval in theMD to the outer body 20 formed through the sealing devices 60 and 61 inthe inner body attachment process 302, and is joined to the outer body20 using appropriate means such as a hot-melt adhesive, heat sealing,etc. In this way, inner assembly bodies 10 and 20 are formed.Subsequently, in the leg opening punching process 303, leg openings areformed in order by a cutter device 63. Then, in the folding process 304,the inner assembly bodies 10 and 20 are folded at a center in the CD(horizontal direction orthogonal to the MD). Then, in the side portionjoining/separation process 305, the outer body 20 of the front body Fand the outer body 20 of the back body B are joined at portionscorresponding to both side portions of the individual diapers DP to formthe side seal portions 21, and the outer body 20 is cut at a boundary ofthe individual diapers to obtain the individual diapers DP.

When the sheet bond portions 40 and the through holes 31 aresimultaneously formed by welding as described above, it is possible toappropriately determine a relation of a melting point of the elasticfilm 30, melting points of the first sheet layer 20A and the secondsheet layer 20B, and a processing temperature at a welding position.However, rather than to set the melting points of the first sheet layer20A and the second sheet layer 20B to be lower than or equal to themelting point of the elastic film 30, melt and combine the whole of thefirst sheet layer 20A and the second sheet layer 20B and the wholeelastic film 30 at the welding positions, and form the sheet bondportions 40, it is preferable to set the melting points of the firstsheet layer 20A and the second sheet layer 20B to be higher than themelting point of the elastic film 30, melt the elastic film 30 at thewelding position, and not to melt a part of the first sheet layer 20Aand the second sheet layer 20B or not to melt a whole of the first sheetlayer 20A and the second sheet layer 20B. In other words, as understoodfrom FIG. 31 and FIG. 32 , a latter case corresponds to a structure inwhich fibers 20 f of the first sheet layer 20A and the second sheetlayer 20B continuing from around the sheet bond portions 40 are left,and the first sheet layer 20A and the second sheet layer 20B are joinedby the melted and solidified material 30 m of the elastic film 30, whichhas infiltrated and solidified among the first sheet layer 20A and thesecond sheet layer 20B. Further, improved adhering of the melted andsolidified material of the elastic film to the first sheet layer and thesecond sheet layer is obtained, and strength of the first sheet layer20A and the second sheet layer 20B rarely decreases. Thus, peelingstrength is further enhanced. This situation in which “a part of thefirst sheet layer 20A and the second sheet layer 20B is not melted”includes a mode in which for all fibers of the sheet bond portions 40, acore (including a central portion of each component fiber of a conjugatefiber in addition to a core of the conjugate fiber) remains while asurrounding portion (including a portion on a surface layer side of eachcomponent fiber of a conjugate fiber in addition to a sheath in theconjugate fiber) melts; a mode in which some fibers do not melt at allwhile all remaining fibers melt; or a mode in which a core remains whilea surrounding portion melts.

From this point of view, the melting point of the elastic film 30 ispreferably about 80 to 145° C., melting points of the first sheet layer20A and the second sheet layer 20B are preferably about 85 to 190° C.,particularly, 150 to 190° C., and a difference between the meltingpoints of the first sheet layer 20A and the second sheet layer 20B andthe melting point of the elastic film 30 is preferably about 60 to 80°C.

Meanwhile, an example illustrated in FIG. 22 and FIG. 23 is an examplein which the elastic film stretchable structure 20X is applied to astretchable structure other than the waist end portion region 23 of theouter body 20. However, appropriate changes are allowed. For example,the waist end portion region 23 may be included at the time ofapplication as in the example illustrated in FIG. 1 and FIG. 2 and theexample illustrated in FIG. 33 , or it is possible to adopt a mode inwhich the elastic film stretchable structure 20X is not provided in theintermediate region L between the torso region T of the front body F andthe torso region T of the back body B. In addition, the above-describedstretchable structure 20X may be applied to another elastic portion suchas a three-dimensional gather, a plane gather, etc. generally used for awaist portion, a fastening tape, and an absorbent article of a tape-typedisposable diaper in addition to the underpants-type disposable diaper.In addition, even though the non-stretchable region 70 is included inthe present embodiment, it is possible to adopt a mode in which thewhole stretchable structure 20X of the elastic film 30 is used as thestretchable region 80 and the non-stretchable region 70 is not included.Furthermore, even though the stretching and contracting direction isregarded as the width direction in the illustrated example, thestretching and contracting direction may be set to front-back directionor set to both the width direction and the front-back direction.

Third Mode

Next, a third mode will be described with reference to FIG. 3 , FIG. 5to FIG. 7 , FIG. 16 , FIG. 21 , FIG. 22 , FIG. 24 , FIG. 31 to FIG. 34 ,and FIG. 35 to FIG. 41 . In the outer body 20, as illustrated in FIG. 16, FIG. 5 , and FIG. 6 , the elastic film 30 and the elongated elasticmember 24 along the width direction are arranged between the first sheetlayer 20A and the second sheet layer 20B, and elasticity in the widthdirection is imparted. The planar shape of the outer body 20 correspondsto a pseudo-hourglass shape as a whole due to the concave leg lines 29formed to form leg openings at intermediate both side portions,respectively. The outer body 20 may be divided into two front and backparts, and the both parts may be separated from each other in thefront-back direction in the crotch portion.

More specifically, in the outer body 20 of the illustrated mode, thewaist end portion elastic member 24 is provided in the waist end portionregion 23 in the torso region T determined as a vertical direction rangeof each side seal portion 21 in which the front body F and the back bodyB are joined. The waist end portion elastic members 24 of theillustrated mode correspond to elongated elastic members such as aplurality of rubber threads disposed at intervals in the verticaldirection, and apply a stretching force to tighten around the waist ofthe body. The waist end portion elastic members 24 are not disposedsubstantially in a bundle with a close spacing, and three or more,preferably five or more members are disposed at intervals of about 3 to8 mm to form a predetermined stretchable zone. A stretch rate of thewaist end portion elastic member 24 in fixing may be appropriatelydetermined. However, the stretch rate may be set to about 230 to 320% inthe case of normal adult use. One or a plurality of belt shaped elasticmembers may be used as the waist end portion elastic member 24.

The rubber threads are used as the waist end portion elastic member 24in an illustrated example. However, for example, a tape shaped elasticmember may be used, and an elastic film described below may be extendedto the waist end portion region 23 instead of using the tape shapedelastic member. The waist end portion elastic member 24 in theillustrated mode is interposed in the folded part 20C formed by foldingback a component of the second sheet layer 20B to the internal surfaceside at the waist opening edge. However, the waist end portion elasticmember 24 may be interposed between a component of the first sheet layer20A and the component of the second sheet layer 20B.

In the present mode, as illustrated in FIG. 35 (a plan view on theinternal surface side corresponding thereto is FIG. 22 ), the elasticfilm stretchable structure 20X is formed in the torso region T of thefront body F and the torso region T of the back body B in the outer body20, and the intermediate region L therebetween. That is, in thestretchable structure 20X of the outer body 20, the non-stretchableregion 70 is provided in an intermediate portion in the width directionincluding a portion overlapping the absorber 13 (which may be a part ora whole of the overlapping portion, and desirably includes substantiallythe whole inner body fixed part 10B), and a portion extended to both theside seal portions 21 at both sides thereof in the width directioncorresponds to the stretchable region 80. Further, over the whole of thestretchable region 80 and the non-stretchable region 70, as illustratedin FIG. 16 and FIG. 5 to FIG. 7 , the elastic film 30 is stacked betweenthe first sheet layer 20A and the second sheet layer 20B, and the firstsheet layer 20A and the second sheet layer 20B are joined via thethrough holes 31 formed in the elastic film 30 by the large number ofsheet bond portions 40 arranged at intervals in the stretching andcontracting direction and the direction orthogonal thereto (the widthdirection and the front-back direction in the underpants-type disposablediaper as in the illustrated mode) in a state in which the elastic film30 is stretched in the width direction. In this case, it is desirablethat the first sheet layer 20A is not and the second sheet layer 20B isnot joined to the elastic film 30 (except for a melted and solidifiedmaterial described below). However, joining is allowed.

In the stretchable region 80, as illustrated in FIG. 7D, in the naturallength state of the elastic film 30, the first sheet layer 20A and thesecond sheet layer 20B between each pair of adjacent sheet bond portionsrise in a direction away from each other, and thus a contraction wrinkle25 extending in a direction intersecting the stretching and contractingdirection is formed. As illustrated in FIG. 7C, in a worn state of beingstretching to some extent in the width direction, the contractionwrinkle 25 is left even though the contraction wrinkle 25 is stretched.In addition, as in the illustrated modes, when the first sheet layer 20Ais not and the second sheet layer 20B is not joined to the elastic film30 in a portion other than at least between the first sheet layer 20Aand the second sheet layer 20B, as understood from FIG. 7C assuming theworn state and FIGS. 7A and 7B assuming a completely spread state of thefirst sheet layer 20A and the second sheet layer 20B, in these states, agap is formed between each sheet bond portion 40 and each through hole31 for the sheet bond portion in the elastic film 30, thus, airpermeability is imparted due to the gap even when a material of theelastic film 30 corresponds to a non-porous film or a sheet. States ofthe contraction wrinkle 25 in the worn state and the natural lengthstate are shown in sample photographs of FIG. 40 and FIG. 41 . Theelongation at the elastic limit of the stretchable region 80 may beadjusted by the area rate of the sheet bond portions 40. In general, theelongation at the elastic limit of the stretchable region 80 in thestretching and contracting direction is desirably set to 200% or more(preferably 265 to 295%).

Characteristically, as illustrated in FIG. 36 , since the area rate ofthe sheet bond portions 40 in the non-stretchable region 70 is higherthan that in the stretchable region 80, and a part or total of a portionformed among the through holes 31 in the elastic film 30 is set to athermal deterioration portion 32 in which elasticity is decreased due tothermal deterioration, an elongation at an elastic limit in thestretching and contracting direction is set to 130% or less (preferably120% or less, more preferably 100%). In the non-stretchable region 70,as understood from the sample photographs of FIG. 40 and FIG. 41 , aportion raised in a stripe shape or an extremely fine wrinkle is formedbetween the two adjacent sheet bond portions 40. However, since the arearate of the sheet bond portions 40 is significantly high, and theportion formed among the sheet bond portions 40 corresponds to thethermal deterioration portion 32 due to thermal deterioration of theelastic film 30, elasticity is substantially eliminated. Furthermore,continuity of the elastic film 30 in the stretchable region 80 and thenon-stretchable region 70 may be maintained, and the appearance becomesexcellent.

A shape of each of the sheet bond portions 40 and the through holes 31in the natural length state may be set to an arbitrary shape such as aperfect circle, an ellipse, a polygon such as a rectangle (including alinear shape or a rounded corner), a star shape, a cloud shape, etc.

A size of each of the sheet bond portions 40 may be appropriatelydetermined. However, when the size is excessively large, an influence ofhardness of the sheet bond portions 40 on a sense of touch increases.When the size is excessively small, a joining area is small, andmaterials may not be sufficiently attached to each other. Thus, ingeneral, an area of each of the sheet bond portions 40 is preferably setto about 0.14 to 0.75 mm². An area of an opening of each of the throughholes 31 may be greater than or equal to that of the sheet bond portionssince the sheet bond portions are formed via the through holes 31.However, the area is preferably set to about 1 to 1.5 times the area ofeach of the sheet bond portions 40. The area of the opening of each ofthe through holes 31 refers to a value obtained when the stretchablestructure 20X is in the natural length state, and refers to a minimumvalue in a case in which the area of the opening of each of the throughholes 31 is not uniform in a thickness direction such as a case in whichthe area is different between a front side and a back side of theelastic film 30.

In general, the area of each of the sheet bond portions and the arearate of the sheet bond portions 40 in each region are preferably set toas below.

(Non-Stretchable Region 70)

Area of each of sheet bond portions 40: 0.14 to 0.75 mm² (particularly0.14 to 0.35 mm²)

Area rate of sheet bond portions 40: 8 to 17% (particularly 9 to 14%)

(Stretchable Region 80)

Area of each of sheet bond portions 40: 0.14 to 3.5 mm² (particularly0.14 to 1.0 mm²)

Area rate of sheet bond portions 40: 1.8 to 19.1% (particularly 1.8 to10.6%)

When the area rate of the sheet bond portions 40 is made differentbetween the non-stretchable region 70 and the stretchable region 80 asdescribed above, the number of sheet bond portions 40 per unit area maybe changed as illustrated in FIG. 37A, or the area of each of the sheetbond portions 40 may be changed as illustrated in FIG. 37B. In a formercase, the area of each of the sheet bond portions 40 may be the same ordifferent between the non-stretchable region 70 and the stretchableregion 80. In a latter case, the number of sheet bond portions 40 perunit area may be the same or different between the non-stretchableregion 70 and the stretchable region 80.

A planar array of the sheet bond portions 40 and the through holes 31may be appropriately determined. However, it is preferable to adopt aplanar array in which the sheet bond portions 40 and the through holes31 are regularly repeated. In addition to the planar array in which thesheet bond portions 40 and the through holes 31 are regularly repeatedsuch as an oblique lattice shape illustrated in FIG. 21A, a hexagonallattice shape illustrated in FIG. 21B (these shapes are also referred toas a staggered shape), a square lattice shape illustrated in FIG. 21C, arectangular lattice shape illustrated in FIG. 21D, a parallel bodylattice shape illustrated in FIG. 21E (a mode in which two groups areprovided such that a large number of parallel oblique row groupsintersect each other as illustrated in the figure), etc. (including amode in which these shapes are inclined at an angle less than 90 degreeswith respect to the stretching and contracting direction), it ispossible to adopt a planar array in which a group of the sheet bondportions 40 (arrangement of a group unit may be regular or irregular,and a pattern, a letter shape, etc. may be used) is regularly repeated.An arrangement mode of the sheet bond portions 40 and the through holes31 may be the same or different between the stretchable region 80 andthe non-stretchable region 70.

As illustrated in FIG. 38 , in addition to the portion overlapping theabsorber 13, for example, it is possible to provide the non-stretchableregion 70 in which the sheet bond portions 40 are disposed in a shape ofan indication 71. The indication 71 may correspond to an indicationknown in a field of the absorbent article, for example, a pattern fordecoration (including a tiny picture or a character), a functionindicator such as a usage method, usage assistance, a size, etc., or amark indication such as a manufacturer, a product name, a characteristicfunction, etc. In an illustrated mode, the applied indication 71 is aflower pattern corresponding to a plant pattern. However, it is possibleto use various types of patterns such as an abstract pattern, an animalpattern, and a natural phenomenon pattern.

As long as elasticity of a part or total of a portion formed among thethrough holes 31 in the elastic film 30 is decreased due to the thermaldeterioration in the non-stretchable region 70, joining of the firstsheet layer 20A and the second sheet layer 20B in the sheet bond portion40 is not particularly restricted. For example, joining of the firstsheet layer 20A and the second sheet layer 20B in the sheet bond portion40 may be performed using a hot-melt adhesive or using joining meansbased on material welding such as heat sealing, ultrasonic sealing, etc.When the joining means based on material welding is used, the throughholes of the elastic film may be formed by protrusions, and the firstsheet layer 20A and the second sheet layer 20B may be directly joined bywelding at positions of the through holes as in Patent Literature 1.However, there is a concern that since the peeling strength is low,peeling may occur when a strong force is applied. In addition, in PatentLiterature 1, since the through holes of the elastic film are formed byprotrusions, the elastic film 30 is not left between the first sheetlayer 20A and the second sheet layer 20B as illustrated in FIG. 24B, andthere is a concern that protrusion debris (not illustrated) may bemovably left around the through holes 31.

Therefore, when the joining means based on material welding is used, itis preferable to adopt a mode in which the first sheet layer 20A and thesecond sheet layer 20B in the sheet bond portions 40 are joined by atleast the melted and solidified material 30 m of the elastic film 30among the first sheet layer 20A and the second sheet layer 20B asillustrated in FIG. 24A. When the first sheet layer 20A and the secondsheet layer 20B are joined using the melted and solidified material 30 mof the elastic film 30 as an adhesive as described above, separationstrength is high, and it is possible to achieve both high airpermeability and high separation strength.

In such a joining structure, for example, when welding is performed in apredetermined pattern of the sheet bond portions 40 in the stretchableregion 80 and the non-stretchable region 70 in a state in which theelastic film 30 is interposed between the first sheet layer 20A and thesecond sheet layer 20B while being stretched in the stretching andcontracting direction at a substantially uniform stretch rate in thedirection orthogonal to the stretching and contracting direction asillustrated in FIG. 33 and FIG. 34 , the elastic film 30 is melted at alarge number of positions to form the through holes 31. At the sametime, manufacture may be simply and efficiently performed using a schemeof joining the first sheet layer 20A and the second sheet layer 20B bysolidification of at least a melted material of the elastic film 30 atpositions of the through holes 31. In the stretchable region 80 and thenon-stretchable region 70 manufactured by this scheme, the shape/area ofeach of the sheet bond portions 40 is substantially equal to theshape/area of each of the through holes 31 in the natural length state.Further, at the time of performing welding of the stretchable region 80and the non-stretchable region 70 using this scheme, when the area rateof the sheet bond portions 40 in the non-stretchable region 70 is higherthan that in the stretchable region 80, and heat of welding istransferred to a part or total of a portion formed among the throughholes 31 in the elastic film 30, the part or total of the portion formedamong the through holes 31 deteriorates due to the heat of welding todecrease elasticity. In this way, it is possible to form thenon-stretchable region 70 having the above-described thermaldeterioration portion 32. Therefore, it is possible to significantlysimply and efficiently manufacture the stretchable structure 20X of theelastic film 30 having the stretchable region 80 and the non-stretchableregion 70. In addition, the manufactured stretchable region 80 achievesboth high air permeability and high separation strength.

FIG. 33 illustrates an example of a method of manufacturing theunderpants-type disposable diaper. This production line corresponds to ahorizontal flow mode in which the width direction of the diaper is theMD (machine direction, line flow direction), and the outer body 20 isformed thereon. After the inner body 10 manufactured on another line isattached to the outer body 20, both side portions of front and backouter bodies 20 are joined by folding at a center in the front-backdirection, and division into individual diapers DP is performed. For thesake of easy understanding, the same name and reference symbol as thoseof a member after manufacture are used for members that are continuousin a manufacturing process.

More specifically, this production line includes an outer body assemblyprocess 301, an inner body attachment process 302, a leg openingpunching process 303, a folding process 304, and a side portionjoining/separation process 305. Among these processes, the outer bodyassembly process 301 is a characteristic process. In more detail, in theouter body assembly process 301, as enlarged and illustrated in FIG. 34, the first sheet layer 20A and the second sheet layer 20B continuing ina belt shape at a predetermined width are fed to sealing devices 60 and61 and such that the first sheet layer 20A and the second sheet layer20B are bonded along a continuing direction thereof, and the elasticfilm 30 continuing in a belt shape at a predetermined width passesthrough a nip roll 90 corresponding to a slower feed speed than speedsof the sealing devices 60 and 61 and are fed to the sealing devices 60and 61 by being interposed between the first sheet layer 20A and thesecond sheet layer 20B in a state of being stretched in the MD due to aspeed difference. In an illustrated mode, one sheet material issegmented into two parts by a slitter 62 to feed the first sheet layer20A as separate front and back parts. However, the sheet material may befed as separate front and back parts, and an integrated front and backsheet material may be fed similarly to the second sheet layer 20Bwithout separating the first sheet layer 20A into front and back parts.Similarly, in the illustrated mode, one elastic film 30 is segmentedinto two parts by the slitter 62 to feed the elastic film 30 as separatefront and back parts. However, the elastic film 30 may be fed asseparate front and back parts, and an integrated front and back elasticfilm 30 may be fed without separating the elastic film 30 into front andback parts.

In the sealing devices 60 and 61, the first sheet layer 20A, the elasticfilm 30 stretched in the MD, and the second sheet layer 20B areinterposed by a seal roll 60 having a large number of pressingprotrusions 60 p arranged in a pattern of the sheet bond portions 40 inthe stretchable region 80 and the non-stretchable region 70 describedabove on an outer circumference surface, and an anvil roll 61 which isdisposed to face the seal roll 60 and has a smooth surface. Further, theelastic film 30 is melted only sites where it is pressed in thethickness direction between the pressing protrusions 60 p and an outercircumference surface of the anvil roll 61 by heating the pressingprotrusions 60 p, thereby forming the through holes 31, and the firstsheet layer 20A and the second sheet layer 20B are bonded by welding atpositions of the through holes 31. A heat sealing device is assumed tobe used as the sealing devices 60 and 61 of the illustrated mode.However, it is possible to use another device such as an ultrasonicsealing device.

Thereafter, the underpants-type disposable diaper may be formed byadopting a known manufacturing process. In the illustrated mode, theinner body 10 manufactured on another line is fed at a predeterminedinterval in the MD to the outer body 20 formed by the sealing devices 60and 61 in the inner body attachment process 302, and is joined to theouter body 20 using appropriate means such as a hot-melt adhesive, heatsealing, etc. In this way, inner assembly bodies 10 and 20 are formed.Subsequently, in the leg opening punching process 303, leg openings areformed in order by the cutter device 63. Then, in the folding process304, the inner assembly bodies 10 and 20 are folded at a center in theCD (horizontal direction orthogonal to the MD). Then, in the sideportion joining/separation process 305, the outer body 20 of the frontbody F and the outer body 20 of the back body B are joined at portionscorresponding to both side portions of each diaper DP to form the sideseal portions 21, and the outer body 20 is cut at a boundary of theindividual diapers to obtain the individual diapers DP.

In a case in which welding for forming the through holes 31 and thesheet bond portions 40 is performed using ultrasonic sealing (ultrasonicwelding), and elasticity of the non-stretchable region 70 is decreasedusing heat thereof, ultrasonic vibration is easily transferred, and asufficient thermal deterioration area of the elastic film 30 may beensured by increasing the area of each of the sheet bond portions 40 inthe non-stretchable region 70 to some extent under a condition that aspeed of the production line is low (about 30 m/min). However, under acondition that the speed of the production line is high (about 120m/min), there is a concern that welding of the sheet bond portions 40may be insufficient when the area of each of the sheet bond portions 40is not decreased to some extent. However, when the area of each of thesheet bond portions 40 is decreased to merely sufficiently weld thesheet bond portions 40, there is a concern that the thermaldeterioration area of the elastic film 30 may be insufficient fornon-stretching. On the other hand, when the area of each of the sheetbond portions 40 in the non-stretchable region 70 is set to 0.14 to 0.75mm², and the area rate of the sheet bond portions 40 in thenon-stretchable region 70 is set 8 to 17% as described above, ultrasonicwelding is performed by densely disposing small sheet bond portions 40at a narrow interval, and there is little concern about insufficientwelding. Further, even though the thermal deterioration area of theelastic film 30 is small, an interval of the adjacent two through holes31 narrows, and thus non-stretching is sufficiently obtained. The abovedescription is similarly applied when the area of each of the sheet bondportions 40 in the non-stretchable region 70 is set 0.14 to 0.75 mm²,and each of an interval 40 m of the adjacent two sheet bond portions 40in the non-stretchable region 70 in the stretching and contractingdirection (MD) and an interval 40 c thereof in the direction orthogonalto the stretching and contracting direction (CD) is set to 1 mm or less.

In addition, in a case in which welding for forming the through holes 31and the sheet bond portions 40 is performed using ultrasonic sealing(ultrasonic welding), and elasticity of the non-stretchable region 70 isdecreased using heat thereof, when the shape of the sheet bond portions40, that is, a shape of each of the welding portions having a weldingpattern in ultrasonic welding is set to a shape that is long in the MDas illustrated in FIGS. 39B and 39C, it is possible to widen the thermaldeterioration area of the elastic film 30 when compared to an isotropicshape having the same area, and an area in which ultrasonic vibration issimultaneously applied does not increase when compared to a shape thatis long in the CD as illustrated in FIG. 39A. Thus, there is anadvantage that welding of the sheet bond portions 40 is less likely tobe insufficient. For example, the shape that is long in the MD refers toan ellipse whose long axis is less than 45 degrees with respect to theMD, a polygon (including a linear shape or a rounded corner) such as arectangle whose long side is less than 45 degrees with respect to theMD, a cloud shape whose longitudinal direction is less than 45 degreeswith respect to the MD, etc.

When the sheet bond portions 40 and the through holes 31 aresimultaneously formed by welding as described above, it is possible toappropriately determine a relation of a melting point of the elasticfilm 30, melting points of the first sheet layer 20A and the secondsheet layer 20B, and a processing temperature at a welding position.However, rather than to set the melting points of the first sheet layer20A and the second sheet layer 20B to be lower than or equal to themelting point of the elastic film 30, melt and combine the whole of thefirst sheet layer 20A and the second sheet layer 20B and the wholeelastic film 30 at the welding positions, and form the sheet bondportions 40, it is preferable to set the melting points of the firstsheet layer 20A and the second sheet layer 20B to be higher than themelting point of the elastic film 30, melt the elastic film 30 at thewelding position, and not to melt a part of the first sheet layer 20Aand the second sheet layer 20B or not to melt a whole of the first sheetlayer 20A and the second sheet layer 20B. In other words, as understoodfrom FIG. 31 and FIG. 32 , a latter case corresponds to a structure inwhich fibers 20 f of the first sheet layer 20A and the second sheetlayer 20B continuing from around the sheet bond portions 40 are left,and the first sheet layer 20A and the second sheet layer 20B are joinedby the melted and solidified material 30 m of the elastic film 30, whichhas infiltrated and solidified among the first sheet layer 20A and thesecond sheet layer 20B. Further, improved adhering of the melted andsolidified material of the elastic film to the first sheet layer and thesecond sheet layer is obtained, and strength of the first sheet layer20A and the second sheet layer 20B rarely decreases. Thus, peelingstrength is further enhanced. This situation in which “a part of thefirst sheet layer 20A and the second sheet layer 20B is not melted”includes a mode in which for all fibers of the sheet bond portions 40, acore (including a central portion of each component fiber of a conjugatefiber in addition to a core of the conjugate fiber) remains while asurrounding portion (including a portion on a surface layer side of eachcomponent fiber of a conjugate fiber in addition to a sheath in theconjugate fiber) melts; a mode in which some fibers do not melt at allwhile all remaining fibers melt; or a mode in which a core remains whilea surrounding portion melts.

From this point of view, the melting point of the elastic film 30 ispreferably about 80 to 145° C., melting points of the first sheet layer20A and the second sheet layer 20B are preferably about 85 to 190° C.,particularly, 150 to 190° C., and a difference between the meltingpoints of the first sheet layer 20A and the second sheet layer 20B andthe melting point of the elastic film 30 is preferably about 60 to 80°C.

An example illustrated in FIG. 2 , FIG. 35 , etc. is an example in whichthe elastic film stretchable structure 20X is applied to a stretchablestructure other than the waist end portion region 23 of the outer body20. However, appropriate changes are allowed. For example, the waist endportion region 23 may be included at the time of application as in theexample illustrated in FIG. 1 and FIG. 2 and the example illustrated inFIG. 33 , or it is possible to adopt a mode in which the elastic filmstretchable structure 20X is not provided in the intermediate region Lbetween the torso region T of the front body F and the torso region T ofthe back body B. In addition, the above-described stretchable structure20X may be applied to another elastic portion such as athree-dimensional gather, a plane gather, etc. generally used for awaist portion, a fastening tape, and an absorbent article of a tape-typedisposable diaper in addition to the underpants-type disposable diaper.In addition, even though the non-stretchable region 70 is included inthe present embodiment, it is possible to adopt a mode in which thewhole stretchable structure 20X of the elastic film 30 is used as thestretchable region 80 and the non-stretchable region 70 is not included.Furthermore, even though the stretching and contracting direction isregarded as the width direction in the illustrated example, thestretching and contracting direction may be set to front-back directionor set to both the width direction and the front-back direction.

<Formation Test of Non-Stretchable Region>

A spunbond nonwoven fabric having a basis weight of 17 g/m², which usesa PE/PP conjugate fiber having a fineness of 1.7 to 1.9 dtex (core:polypropylene (melting point 165° C.), sheath: polyethylene (meltingpoint 130° C.)) as a raw material, was used as the first sheet layer 20Aand the second sheet layer 20B, and a product name MD3 (basis weight 35g/m², thickness: 0.04 mm, melting point: 90 to 100° C.) manufactured byExten Corporation was used as the elastic film 30. In a state in whichthe MD of the nonwoven fabric is set to the stretching and contractingdirection, and the elastic film is stretched 3.5 times in the MD, thethrough holes 31 and the rectangular sheet bond portions 40 having alength 40 m in the MD of 1 mm, a length 40 c in the CD of 0.5 mm, and anarea of 0.5 mm² were formed in the pattern illustrated in FIG. 39B andat various intervals shown in Table 1 using ultrasonic sealing. Then, anelongation at an elastic limit was measured. Ultrasonic sealing was setbased on a condition that a PE layer of fibers of the elastic film, thefirst sheet layer, and the second sheet layer melts. As a result, asshown in Table 1, it was found that when an interval of the adjacent twosheet bond portions in the MD is 1 mm or less, and an interval thereofin the CD is 1 mm or less, elasticity is eliminated due to thermaldeterioration of a most part between the through holes, andnon-stretching is obtained.

TABLE 1 Interval in MD 0.25 0.5 0.75 1 1.25 1.5 2 Interval 0.25 100%(53%) 100% (44%) 100% (38%) — — — — in CD 0.5 100% (40%) 100% (33%) 100%(29%) 123% (25%) — — — 0.75 100% (32%) 100% (27%) 112% (28%) 141% (20%)158% (18%) — — 1 — 115% (22%) 128% (19%) 160% (17%) 160% (16%) 184%(18%) — 1.25 — — 144% (16%) 167% (14%) 174% (13%) 218% (11%) 246% (9.6%)1.5 — — — 170% (13%) 207% (11%) 244% (10%) 251% (8.3%) 2 — — — — 219%(8.9%) 245% (8.0%) 256% (6.7%) ※In the table, a value in bracketscorresponds to an area rate of each of the joint portions.

Fourth Mode

Next, a fourth mode will be described with reference to FIG. 3 to FIG. 7, FIG. 16 , FIG. 37 , FIG. 38 , and FIG. 42 to FIG. 52 . In the outerbody 20, as illustrated in FIG. 4 to FIG. 6 , the elastic film 30 isarranged between the first sheet layer 20A and the second sheet layer20B, and elasticity in the width direction is imparted. The planar shapeof the outer body 20 corresponds to a pseudo-hourglass shape as a wholedue to the concave leg line 29 formed to form leg openings atintermediate both side portions, respectively. The outer body 20 may bedivided into two front and back parts, and the both parts may beseparated from each other in the front-back direction in the crotchportion.

Characteristically, as illustrated in FIG. 43 , the stretchablestructure 20X of the invention is formed in the torso region T of thefront body F, the torso region T of the back body B, and theintermediate region L therebetween in the outer body 20. In other words,the elastic film 30 is stacked between the first sheet layer 20A and thesecond sheet layer 20B in the stretchable structure 20X of the outerbody 20, and a region having this elastic film stretchable structure 20Xincludes the non-stretchable region 70 and the stretchable region 80stretchable in the width direction provided at least at one side of thenon-stretchable region 70 in the stretching and contracting direction(width direction). The stretchable region 80 has an elongation at anelastic limit in the width direction of 200% or more (preferably 265 to295%) when the first sheet layer 20A and the second sheet layer 20B aredirectly or indirectly joined at the large number of sheet bond portions40 arranged at intervals in the width direction and the verticaldirection orthogonal thereto (the stretching and contracting directionand the direction orthogonal thereto) in a state in which the elasticfilm 30 is stretched in the width direction along surfaces thereof.Meanwhile, the non-stretchable region 70 has an elongation at an elasticlimit in the width direction of 130% or less (preferably 120% or less,more preferably 100%) when the first sheet layer 20A and the secondsheet layer 20B are directly or indirectly joined at the large number ofsheet bond portions 40 arranged at intervals in the width direction andthe vertical direction orthogonal thereto, and the area rate of thesheet bond portions 40 is higher than that in the stretchable region 80in a state in which the elastic film 30 is stretched in the widthdirection along surfaces thereof.

When the first sheet layer 20A and the second sheet layer 20B aredirectly or indirectly joined at the large number of sheet bond portions40 arranged at intervals in the stretching and contracting direction andthe direction orthogonal thereto in a state in which the elastic film 30is stretched in the width direction in such an elastic film stretchablestructure 20X, basically, as the area rate of the sheet bond portions 40increases, a portion in which the first sheet layer 20A and the secondsheet layer 20B contract by the elastic film 30 decreases. Thus, anelongation at an elastic limit tends to decrease. Therefore, thenon-stretchable region 70 and the stretchable region 80 may be formedonly by changing the area rate of the sheet bond portions 40 using sucha characteristic.

In this case, in the stretchable region 80, as illustrated in FIG. 7D,in the natural length state of the elastic film 30, the first sheetlayer 20A and the second sheet layer 20B between each pair of adjacentsheet bond portions rise in a direction away from each other, and thus acontraction wrinkle 25 extending in a direction intersecting thestretching and contracting direction is formed. As illustrated in FIG.7C, in a worn state of being stretching to some extent in the widthdirection, the contraction wrinkle 25 is left even though thecontraction wrinkle 25 is stretched. In addition, as in the illustratedmodes, when the first sheet layer 20A is not and the second sheet layer20B is not joined to the elastic film 30 in a portion other than atleast between the first sheet layer 20A and the second sheet layer 20B,as understood from FIG. 7C assuming the worn state and FIGS. 7A and 7Bassuming a completely spread state of the first sheet layer 20A and thesecond sheet layer 20B, in these states, a gap is formed between eachsheet bond portion 40 and each through hole 31 for the sheet bondportion in the elastic film 30, thus, air permeability is imparted dueto the gap even when a material of the elastic film 30 corresponds to anon-porous film or a sheet.

In a case in which the non-stretchable region 70 is formed when the arearate of the sheet bond portions 40 in the non-stretchable region 70 ishigher than that in the stretchable region 80, a raised portion or anextremely fine wrinkle is formed between sheet bond portions 40 in thenon-stretchable region 70. However, since the area rate of the sheetbond portions 40 is significantly high, elasticity is substantiallyeliminated. In addition, the non-stretchable region 70 may be formed byheating and melting the elastic film 30. In this case, when the sheetbond portions 40 are formed in the non-stretchable region 70, the arearate of the sheet bond portions 40 may be higher or lower than that inthe non-stretchable region 70. For example, it is possible to provideonly the sheet bond portions 40 arranged in a display shape to form adisplay portion 71 described below. Further, the non-stretchable region70 may be formed by finely dividing the elastic film 30 at least in thestretching and contracting direction. Such division may be performed byforming the sheet bond portions 40 in a net shape or a stripe shapeintersecting the stretching and contracting direction, or cutting theelastic film 30 in a net shape or a stripe shape intersecting thestretching and contracting direction using pressing, etc.

Further, in the region having the elastic film stretchable structure20X, when a configuration in which the stretchable region 80 is notpresent at both sides of the non-stretchable region 70 in the verticaldirection (the direction orthogonal to the stretching and contractingdirection) is adopted, and the display portion 71 comprised of the sheetbond portions 40 is disposed in the middle in the vertical direction, asschematically illustrated in FIG. 45B, the display portion 71 is hardlyaffected by contraction of the stretchable region 80, and degradation ofappearance of the display portion 71 is prevented. On the other hand, asschematically illustrated in FIG. 45A, when the stretchable region 80 isadjacent to the display portion 71 of the non-stretchable region 70 inthe direction orthogonal to the stretching and contracting direction, awrinkle or pleat 75 is formed in the non-stretchable region 70 due to aninfluence of contraction of the stretchable region 80, and appearance ofdisplay is degraded. In the non-stretchable region 70, the displayportion 71 may be provided in a part thereof, and the other part may beset to a non-display portion 72 as in the illustrated mode.Alternatively, the display portion 71 may be provided across the wholenon-stretchable region 70.

The shapes of each of the sheet bond portions 40 and each of the throughportions 31 in the natural length state may be determined such as aperfect circle, an ellipse, a polygon such as a triangle, a rectangle, arhombus, etc., a star shape, a cloud shape, etc. A size of each of thesheet bond portions 40 may be appropriately determined. However, whenthe size is excessively large, an influence of hardness of the sheetbond portions 40 on a sense of touch increases. When the size isexcessively small, a joining area is small, and materials may not besufficiently attached to each other. Thus, in general, an area of eachof the sheet bond portions 40 is preferably set to about 0.14 to 3.5mm². An area of an opening of each of the through portions 31 may begreater than or equal to that of each of the sheet bond portions sincethe sheet bond portions are formed via the through portions 31. However,the area is preferably set to about 1 to 1.5 times the area of each ofthe sheet bond portions. The area of the opening of each of the throughportions 31 refers to a value in a state in which the stretchablestructure corresponds to a natural length, and refers to a minimum valuein a case in which the area of the opening of each of the throughportions 31 is not uniform in the thickness direction such as a case inwhich the area is different between a front side and a back side of theelastic film.

In general, in the case in which the non-stretchable region 70 is formedwhen the area rate of the sheet bond portions 40 is higher than that inthe stretchable region 80, the area of each of the sheet bond portionsand the area rate of the sheet bond portions 40 in each region arepreferably set to as below.

(Non-Stretchable Region 70)

Area of each of sheet bond portions 40: 0.14 to 3.5 mm² (particularly0.25 to 1.0 mm²)

Area rate of sheet bond portions 40: 16 to 45% (particularly 25 to 45%)

(Stretchable Region 80)

Area of each of sheet bond portions 40: 0.14 to 3.5 mm² (particularly0.14 to 1.0 mm²)

Area rate of sheet bond portions 40: 1.8 to 19.1% (particularly 1.8 to10.6%)

When the area rate of the sheet bond portions 40 is made differentbetween the non-stretchable region 70 and the stretchable region 80, thenumber of sheet bond portions 40 per unit area may be changed asillustrated in FIG. 37A, or the area of each of the sheet bond portions40 may be changed as illustrated in FIG. 37B. In a former case, the areaof each of the sheet bond portions 40 may be the same or differentbetween the non-stretchable region 70 and the stretchable region 80. Ina latter case, the number of sheet bond portions 40 per unit area may bethe same or different between the non-stretchable region 70 and thestretchable region 80.

A planar array of the sheet bond portions 40 other than the displayportion 71 may be appropriately determined. However, in order tohighlight the display portion 71, it is preferable to adopt a planararray in which the sheet bond portions 40 are regularly repeated. Inaddition to the planar array in which the sheet bond portions 40 areregularly repeated such as an oblique lattice shape or a hexagonallattice shape (these shapes are also referred to as a staggered shape),a square lattice shape, a rectangular lattice shape, a parallel bodylattice shape (a mode in which two groups are provided such that a largenumber of parallel oblique row groups intersect each other asillustrated in the figure), etc., it is possible to adopt a planar arrayin which a group of the sheet bond portions 40 (arrangement of a groupunit may be regular or irregular, and a pattern, a letter shape, etc.may be used) is regularly repeated. An arrangement mode of the sheetbond portions 40 other than the display portion 71 may be the same ordifferent between the stretchable region 80 and the non-stretchableregion 70.

The display portion 71 may be formed by arranging dot-shaped sheet bondportions 40 in a shape of the display portion 71 as illustrated in FIG.43 , FIG. 47 , and FIG. 48 , and may be formed by forming a single sheetbond portion 40 in the shape of the display portion 71. The shape of thedisplay portion 71 may correspond to an indication known in a field ofthe absorbent article, for example, a pattern for decoration (includinga tiny picture or a character), a function indicator such as a usagemethod, usage assistance, a size, etc., or a mark indication such as amanufacturer, a product name, a characteristic function, etc. In a modeillustrated in FIG. 43 , a flower pattern corresponding to a type ofplant pattern is applied. However, another plant pattern may be applied,and it is possible to use various types of patterns such as an abstractpattern, an animal pattern, and a natural phenomenon pattern.

A scheme of forming the sheet bond portions 40 is not particularlyrestricted. However, when the sheet bond portions 40 are formed bywelding, appearance of the sheet bond portions 40 is different fromsurroundings. Thus, the display portion 71 is highlighted, which ispreferable.

In the sheet bond portion 40, the first sheet layer 20A and the secondsheet layer 20B may be joined directly or indirectly through anothersheet such as the elastic film 30. FIG. 44 illustrates three types ofrepresentative joining structures. In the joining structures illustratedin FIGS. 44A and 44C, similarly to the mode illustrated in FIG. 3 , thefirst sheet layer 20A and the second sheet layer 20B are joined viathrough portions 31 formed in the elastic film 30, and the first sheetlayer 20A is not and the second sheet layer 20B is not joined to theelastic film 30 in a portion other than at least between the first sheetlayer 20A and the second sheet layer 20B in the sheet bond portions 40(area with diagonal lattice pattern in FIG. 44 ). This joining structuremay be manufactured only by using an arrangement pattern of bumps of apatterned calendar roller in a method of JP 2004-532758 A as the patternof the sheet bond portions 40. However, it is considered that the methoddescribed in JP 2004-532758 A pushes out the elastic film 30 withoutmelting the elastic film 30. In this case, as illustrated in FIG. 44C,the elastic film 30 is not left between the first sheet layer 20A andthe second sheet layer 20B, and there is a concern that protrusiondebris (not illustrated) may be movably left around the through portions31.

On the other hand, when the sheet bond portions 40 are formed in thearrangement pattern of the sheet bond portions 40 using a sheet bondportion forming device 100 (an ultrasonic sealing device 101 illustratedin FIG. 46A or a heat sealing device 102 illustrated in FIG. 46B) in astate in which the elastic film 30 is interposed between the first sheetlayer 20A and the second sheet layer 20B as illustrated in FIG. 46 , itis possible to the first sheet layer 20A and the second sheet layer 20Bmay be joined via the through portions 31 simultaneously with formingthe through portions 31 in the elastic film 30, and to efficientlyperform manufacture. In this case, it is possible to obtain a joiningstructure in which a melting separation piece of the elastic film 30 isleft in the sheet bond portions 40 as illustrated in FIG. 44A. Asdescribed above, in a mode in which the melting separation piece of theelastic film 30 is left between the first sheet layer 20A and the secondsheet layer 20B of the sheet bond portions 40, the first sheet layer 20Aand the second sheet layer 20B may be joined to the elastic film 30 inthe sheet bond portions 40. However, the mode correspond to a mode inwhich the first sheet layer 20A is not and the second sheet layer 20B isnot joined to the elastic film 30 in a portion other than at leastbetween the first sheet layer 20A and the second sheet layer 20B in thesheet bond portions 40 (which means that a case in which the first sheetlayer 20A is not and the second sheet layer 20B is not, in the sheetbond portion 40, joined to the surrounding elastic film 30 (that is, anedge portion of the through portions 31) is excluded). In this case, thearea of each of the sheet bond portions is substantially equal to thearea of each of the through portions. In addition, when a type ofmaterial of the elastic film 30 or a processing condition such as aprocessing temperature is appropriately selected such that the elasticfilm 30 is not melted and separated and the through portions 31 are notformed in the sheet bond portions 40 in a manufacturing method describedin JP 2004-532758 A, it is possible to obtain a joining structure inwhich the through portions are not formed in the elastic film 30 and thefirst sheet layer 20A and the second sheet layer 20B are indirectlyjoined through the elastic film 30 in the sheet bond portions 40 asillustrated in FIG. 44B.

The display portion 71 in the non-stretchable region 70 is formed by thesheet bond portions 40. Thus, when the non-stretchable region 70 isformed by making the area rate of the sheet bond portions 40 to behigher than that in the stretchable region 80, and the non-displayportion 72 is provided, a shape, a size, and an angle of each of thesheet bond portions, and an area rate of the sheet bond portions 40 needto be different between the non-display portion 72 and the displayportion 71 as illustrated in FIGS. 47A to 47C. However, in this case,there is a merit that it is sufficient to perform only one process in apattern of the sheet bond portions 40 in all the stretchable region 80,the display portion 71 of the non-stretchable region 70, and thenon-display portion 72 of the non-stretchable region 70 using the sheetbond portion forming device 100 (an ultrasonic sealing deviceillustrated in FIG. 48A or a heat sealing device 102 illustrated in FIG.48B) as illustrated in FIGS. 48A and 48B. In this mode, when the patternof the sheet bond portions 40 in the non-display portion 72 is set to anet shape illustrated in FIG. 49A (or a stripe shape intersecting in thestretching and contracting direction), the elastic film 30 in thenon-display portion 72 may be separated to obtain non-stretching asillustrated in FIG. 47D. However, the sheet bond portions 40 are formedin the same pattern.

When the non-stretchable region 70 is formed by heating and melting theelastic film 30, after a melting temperature of the first sheet layer20A and the second sheet layer 20B is set to be sufficiently higher thana melting temperature of the elastic film 30, at least the sheet bondportions 40 of the display portion 71 are formed by a sheet bond portionforming device 111 (the heat sealing device 102 illustrated in FIG. 46Bmay be used) as illustrated in FIGS. 46C and 46D. Thereafter, the wholenon-stretchable region 70 or the non-display portion 72 is heated by anelastic film melting device 112 (the heat sealing device illustrated inFIG. 46A or the ultrasonic sealing device illustrated in FIG. 46B) to atemperature at which the first sheet layer 20A and the second sheetlayer 20B are not melted and welded and the elastic film 30 is melted.In this way, it is possible to melt only the elastic film 30. When theelastic film 30 is melted across the whole non-stretchable region 70,the area rate of the sheet bond portions 40 in which the display portion71 is formed may not be higher than that in the stretchable region 80.Therefore, the display portion 71 may be formed without restriction asillustrated in FIGS. 48A to 48E. More specifically, in examplesillustrated in FIGS. 48A to 48E, the area rate of the sheet bondportions 40 in the non-display portion 72 is lowered. In the exampleillustrated in FIG. 48A, the area rate of the sheet bond portions 40 inthe display portion 71 is high. In the example illustrated in FIG. 48B,the area rate of the sheet bond portions 40 in the display portion 71 islow. In addition, in the examples illustrated in FIGS. 48C and 48D, thesheet bond portions 40 in the display portion 71 are formed only in asite along an outer circumference of the display portion 71, and thesheet bond portions 40 are not formed on the inside. Further, in theexample illustrated in FIG. 48E, the sheet bond portions 40 areregularly provided in the non-display portion 72, and the sheet bondportions 40 in the display portion 71 are excluded. In this way, thedisplay portion 71 appears. Meanwhile, when the elastic film 30 ismelted only in the non-display portion 72, non-stretching needs to beobtained by setting the area rate of the sheet bond portions 40 formingthe display portion 71 to be higher than that in the stretchable region80.

The elastic film 30 may be divided to obtain non-stretching by formingthe sheet bond portions 40 in the whole non-stretchable region 70 or thenon-display portion 72 in a pattern of the sheet bond portions 40corresponding to the net shape illustrated in FIG. 49A (or a stripeshape intersecting in the stretching and contracting direction) usingthe sheet bond portion forming device 111 instead of the elastic filmmelting device 112. Alternatively, non-stretching may be obtained byforming the dot-shaped sheet bond portions 40 at a high area rate in thewhole non-stretchable region 70 or the non-display portion 72 asillustrated in FIG. 49B. However, when this process is performed in thewhole non-stretchable region 70, a pattern in which the display portion71 is not crushed needs to be adopted.

The modes illustrated in FIG. 42 and FIG. 43 correspond to a mode inwhich the elastic film stretchable structure 20X extends to the waistend portion region 23, and a stretchable structure 20X in another widthdirection is not included in a front and a back of the non-stretchableregion 70. However, when the elastic film stretchable structure 20X isused in the waist end portion region 23, tightening of the waist endportion region 23 is insufficient. It is possible to provide astretchable structure 20X according to a conventional elongated waistend portion elastic member 24 as necessary without providing the elasticfilm stretchable structure 20X in the waist end portion region 23 asillustrated in FIG. 38 (a longitudinal section view correspondingthereto is FIG. 16 ). The waist end portion elastic members 24correspond to elongated elastic members such as a plurality of rubberthreads disposed at intervals in the vertical direction, and apply astretching force to tighten around the waist of the body. The waist endportion elastic members 24 are not disposed substantially in a bundlewith a close spacing, and three or more, preferably five or more membersare disposed at intervals of about 3 to 8 mm to form a predeterminedstretchable zone. A stretch rate of the waist end portion elastic member24 in fixing may be appropriately determined. However, the stretch ratemay be set to about 230 to 320% in the case of normal adult use. Rubberthreads are used as the waist end portion elastic member 24 in anillustrated example. However, for example, another elongated elasticmember such as flat rubber may be used.

In this case, as illustrated in FIG. 38 , it is possible to form thestretchable region 80 in which the elongated waist end portion elasticmember 24 is fixed in a stretched state along the width direction acrossa whole range in the width direction corresponding to a range betweenboth the side seal portions 21. However, when the display portion 71 isprovided near the waist end portion region 23, even though the displayportion 71 is located in the middle in the direction orthogonal to thestretching and contracting direction of the non-stretchable region 70,the display portion 71 is likely to be affected by stretching andcontraction of the waist end portion region 23. Therefore, in apreferable mode, as illustrated in FIG. 50 , in a case that the waistend portion elastic member 24 is provided, the non-stretchable region 70or a weak stretchable region 80 is formed by not providing the waist endportion elastic member 24, cutting finely, cutting in the middle in thewidth direction, or reducing the number, in a region having the elasticfilm stretchable structure 20X of the waist end portion region 23 in awidth direction range corresponding to a width direction range of thedisplay portion 71, more preferably corresponding to a width directionrange of the non-stretchable region 70.

As another mode, it is possible to adopt a mode in which the stretchablestructure 20X is not provided in the intermediate region L between thetorso region T of the front body F and the torso region T of the backbody B.

Arrangement of the stretchable region 80 and the non-stretchable region70 may be appropriately determined. In the case of the outer body 20 ofthe underpants-type disposable diaper as in the present embodiment,since a portion overlapping the absorber 13 is a region not requiringstretching/contracting, it is preferable to form the non-stretchableregion 70 including the display portion 71 including a part or total ofthe portion overlapping the absorber 13 (desirably includingsubstantially the whole inner body fixed part 10B) as in the illustratedmode. A region overlapping the absorber 13 in the outer body 20 is aregion having elasticity and a portion fixed to the absorber 13, andthus is a region in which an influence of contraction of the stretchableregion 80 is relatively small and is suitable for providing the displayportion 71. On the other hand, a region not overlapping the absorber 13does not require elasticity and flexibility, and thus is a regionnaturally not having a display such as a pattern. To this extent, theregion is a region which is significant for providing a display thatimproves appearance. According to the invention, it is possible toprovide the non-stretchable region 70 in such a region to provide thedisplay portion 71 therein. The non-stretchable region 70 may beprovided in both the region overlapping the absorber 13 and the regionnot overlapping the absorber 13, or the non-stretchable region 70 may beprovided in any one of the regions.

From the above viewpoint, a torso intermediate region 26 defined by avertical direction range between the waist end portion region 23 and theabsorber 13 as in the illustrated mode is a region suitable to providethe non-stretchable region 70. In this case, it is possible to form thenon-stretchable region 70 having the display portion 71 in the middle ofthe torso intermediate region 26 in the width direction, and to setwidth direction ranges corresponding to ranges between thenon-stretchable region 70 and both the side seal portions 21 to thestretchable regions 80. Since the middle of the torso intermediateregion 26 in the width direction is a portion at which, when thenon-stretchable region 70 is formed in this portion, and both sidesthereof is used as the stretchable regions 80, a fitting property withrespect to the abdominal bulge of the wearer is excellent. In addition,when the non-stretchable region 70 is continued to the waist end portionregion 23, it is possible to compensate for the fitting property by thestretchable regions 80 on both sides thereof.

Further, it is possible to improve a fitting property with respect to asurface of the body using a shape of the non-stretchable region 70. Forexample, in a case in which the non-stretchable region 70 is provided atthe central part in the width direction in the outer body 20 of theunderpants-type disposable diaper, when the shape of the non-stretchableregion 70 is set to a shape in which a width narrows continuously orstepwise from the crotch side toward the waist opening side asillustrated in FIG. 51A, a fitting property corresponding to a case inwhich the waist is thin is excellent. In addition, when the shape of thenon-stretchable region 70 is set to a shape in which the width narrowscontinuously or stepwise from the crotch side toward the waist openingside as illustrated in FIG. 51B, a fitting property is excellent whenthe abdominal bulge of the wearer is particularly large in the case ofthe front body F and when a bulge of the gluteal region is particularlylarge in the case of the back body B. Further, when the shape of thenon-stretchable region 70 is set to a shape in which the width widensand then narrows continuously or stepwise from the crotch side towardthe waist opening side as illustrated in FIG. 51C, a fitting property isexcellent in a case in which the wearer has a standard body type.

In addition, when a continuous width of the non-stretchable region 70 iswidened, a fitting property and flexibility are degraded. Thus, when theshape of the non-stretchable region 70 is set to a shape branched into aplurality of parts from the crotch side toward the waist opening side,and the stretchable region 80 is provided between both parts of thebranched non-stretchable region 70 as illustrated in FIG. 51D, it ispossible to provide the display portion 71 based on the non-stretchableregion 70 while preventing the outer body 20 from hardening, which ispreferable.

In addition, in a case in which the waist end portion elastic member 24is provided in a width direction range corresponding to the displayportion of the non-stretchable region 70 in the waist end portion region23, when a shape in which the width narrows continuously or stepwisefrom the crotch side toward the waist opening side as illustrated inFIG. 51E is adopted, there is a merit that an influence of stretchingand contraction of the waist end portion region 23 thereon is little.

As explained in these modes, in a case in which the non-stretchableregion 70 is provided in the central part in the width direction in theouter body 20 of the underpants-type disposable diaper and a fittingproperty is improved by this configuration, as illustrated in FIGS. 52Aand 52B, when both side edges of the non-stretchable region 70 arecurved, the fitting property with respect to the surface of the body isfurther improved. A left diagram of FIG. 52 schematically expresses aspread state, and a right diagram thereof schematically expresses anatural length state. In addition, when the non-stretchable region 70 isprovided in both the front body F and the back body B, a shape may bemade different between the front and the back using the mode illustratedin FIG. 52A for the front body F and the mode illustrated in FIG. 52Cfor the back body B, thereby further improving the fitting property withrespect to the body surface.

Others

A part or a whole of any one of the above-described first to fourthmodes may be applied to another mode.

In the above-described first to fourth modes, the first sheet layer 20Aand the second sheet layer 20B may be composed of any sheet members,preferably nonwoven fabrics in view of air permeability and flexibility.The nonwoven fabric may be composed of any raw fiber. Examples of theraw fiber include synthetic fibers, such as olefin fibers, e.g.,polyethylene fibers and polypropylene fibers, polyester fibers, andpolyamide fibers; recycled fibers, such as rayon and cupra; naturalfibers, such as cotton; and blend or conjugate fibers composed of two ormore of these fibers. The nonwoven fabric may be prepared by anyprocess. Examples of such a process include well-known processes, suchas spun lacing, spun bonding, thermal bonding, melt blowing, needlepunching, air-through processes, and point bonding. The nonwoven fabricpreferably has a basis weight of approximately 12 to approximately 20g/m². The first sheet layer 20A and the second sheet layer 20B may becomposed of a pair of facing layers prepared by folding back a singlesheet that is partially or entirely folded back. For example, as in theillustrated mode, in the waist end portion region 23, a componentlocated on the outer side may be used as the second sheet layer 20B, thefolded part 20C formed by folding back to the internal surface side atthe waist opening edge thereof may be used as the first sheet layer 20A,and the elastic film 30 may be interposed therebetween. Further, in theother portion, a component located on the inner side may be used as thefirst sheet layer 20A, a component located on the outer side may be usedas the second sheet layer 20B, and the elastic film 30 may be interposedtherebetween. The components of the first sheet layer 20A and the secondsheet layer 20B may be separately provided across the whole part in thefront-back direction, and the elastic film 30 may be interposed betweenthe component of the first sheet layer 20A and the component of thesecond sheet layer 20B without folding back the components.

The elastic film 30 in the above-described first to fourth modes may becomposed of any thermoplastic resin film having elasticity. It ispossible to use a film in which a large number of holes or slits areformed for ventilation in addition to a nonporous film. For example, itis possible to use a film obtained by processing a blend of one or twoor more types of thermoplastic elastomers such as a styrene typeelastomer, an olefin type elastomer, a polyester type elastomer, apolyamide type elastomer, a polyurethane type elastomer, etc. in a filmshape using extrusion molding such as a T-die method, an inflationmethod, etc. In particular, it is preferable when the elastic film 30has a tensile strength in the width direction (the stretching andcontracting direction, the MID) of 8 to 25 N/35 mm, tensile strength inthe front-back direction (the direction orthogonal to the stretching andcontracting direction, the CD) of 5 to 20 N/35 mm, tensile elongation inthe width direction of 450 to 1,050%, and tensile elongation in thefront-back direction of 450 to 1,400%. The thickness of the elastic film30 is not particularly restricted. However, the thickness is preferablyin a range of about 20 to 40 μm. In addition, the basis weight of theelastic film 30 is not particularly restricted. However, the basisweight is preferably in a range of about 30 to 45 g/m², and particularlypreferably in a range of about 30 to 35 g/m².

<Description of Terms in Specification>

The terms used in the specification have the following meanings unlessotherwise stated.

-   -   The “front body” and the “back body” refer to front and back        portions using the center of the underpants-type disposable        diaper in the front-back direction as a boundary. In addition,        the crotch portion refers to a front-back direction range        including the center of the underpants-type disposable diaper in        the front-back direction, and refers to a front-back direction        range of a portion having a narrower part when the absorber has        the narrower part.    -   The “elongation at the elastic limit” refers to an elongation at        an elastic limit in the stretching and contracting direction (in        other words, a state in which the first sheet layer and the        second sheet layer are completely spread), and expresses a        length at the time of the elastic limit as a percentage when the        natural length is set to 100%.    -   The “area rate” refers to a rate of a target portion to the unit        area, and expresses the rate as a percentage by dividing a total        area of the target portion (for example, the sheet bond portions        40, the openings of the through holes 31, and the vent hole) in        a target region (for example, the stretchable region 80 and the        non-stretchable region 70) by an area of the target region.        Particularly, an area rate in a region having a stretchable        structure (for example, an area rate of sheet bond portions)        refers to an area rate in a state of being stretched in the        stretching and contracting direction to the elastic limit. In a        mode in which a plurality of target portions is provided at        intervals, it is desirable to obtain the area rate by setting        the target region to a size at which ten or more target portions        are included.    -   The area of the opening of each of the through holes refers to a        value obtained when the elastic film stretchable structure is in        a natural length state, and refers to a minimum value in a case        in which the area of the opening of each of the through holes is        not uniform in the thickness direction such as a case in which        the area is different between the front and the back of the        elastic film.    -   The MD refers to a machine direction, that is, a line flow        direction, and the CD refers to a horizontal direction        orthogonal to the MD.    -   The “stretch rate” represents a value relative to the        natural-length (100%)    -   The “Basis weight” is determined as follows: After the sample or        test piece is preliminarily dried, it is allowed to stand in a        testing chamber or machine under the standard condition        (temperature: 20±5° C., relative humidity: 65% or less) until        the constant mass. The preliminary drying represents that the        sample or test piece reaches constant mass in an environment        within a relative humidity of 10 to 25% and at a temperature not        exceeding 50° C. The fiber of an official regain of 0.0% does        not need preliminary drying. A cut sample with a size of 200 mm        by 250 mm (±2 mm) is prepared from the test piece after the        constant mass with a cutting template (200 mm by 250 mm, ±2 mm).        The sample is weighed and the weight is multiplied by 20 into        the weight per square meter. The resulting value is defined as        basis weight.    -   The “thickness” of the absorber is measured using a thickness        measurement apparatus of OZAKI MGF Co., Ltd. (PEACOCK, Dial        Thickness Gauge Large Type, Model J-B (Measurement Range 0 to        35 mm) or Model K-4 (Measurement Range 0 to 50 mm)) by        horizontally disposing a sample and the thickness measurement        apparatus.    -   A “thickness” other than the above-described thickness is        automatically determined with an automatic thickness gauge        (KES-G5 handy compression measurement program) under the        conditions of a load of 10 gf/cm² and a pressurization area of 2        cm².    -   The “tensile strength” and the “tensile elongation at break” are        measured at an initial chuck interval of 50 mm and a speed of        testing of 300 mm/min with a tensile tester (for example,        AUTOGRAPHAGS-G100N available from SHIMADZU) in accordance with        JIS K7127:1999 “Plastics—Determination of tensile properties”,        except that the test piece is a rectangle with a width of 35 mm        and a length of 80 mm.    -   The “stretching stress” indicates the tensile stress (N/35 mm)        when the sample is stretched in an elastic region that is        measured by a tensile test at an initial chuck interval        (distance between two adjacent marked lines) of 50 mm and a        speed of testing of 300 mm/min in accordance with JIS K7127:1999        “Plastic—Determination of tensile properties”, and an extent of        stretching may be appropriately determined depending on the test        object. A test piece is preferably formed in a rectangular shape        having a width of 35 mm and a length of 80 mm or more. If a test        piece with a width of 35 mm cannot be prepared, the test piece        with a maximum possible width is prepared and the observed value        is converted into a value at a width of 35 mm. Even if a        sufficiently large test piece cannot be prepared from a target        region with a small area, small test pieces can also be used for        comparison of the stretching stress. For example,        AUTOGRAPHAGS-G100N manufactured by SHIMADZU may be used as a        tensile tester.    -   The “spread state” refers to a flatly spread state without        contraction or slack.    -   Unless otherwise specified, dimensions of each portion refer to        dimensions in the spread state, not the natural length state.    -   In the absence of description about an environmental condition        in a test or measurement, the test or measurement is performed        in a test room or a device in a standard state (temperature        20±5° C., relative humidity 65% or less in a test location).

INDUSTRIAL APPLICABILITY

An elastic film stretchable structure of the invention is applicable toa waist portion or a fastening tape of a tape-type disposable diaper inaddition to an underpants-type disposable diaper, and to another elasticportion such as a three-dimensional gather, a plane gather, etc.generally used for all absorbent articles including another type ofdisposable diaper such as a pad-type disposable diaper, a sanitarynapkin, etc.

REFERENCE SIGNS LIST

B . . . back body, F . . . front body, T . . . torso region, L . . .intermediate region, 10 . . . inner body, 11 . . . top sheet, 12 . . .liquid impervious sheet, 13 . . . absorber, 13N . . . narrower part, 14. . . package sheet, 15 . . . gather nonwoven fabric, 16 . . . gatherelastic member, 20 . . . outer body, 20A . . . first sheet layer, 20B .. . second sheet layer, 20C . . . folded part, 20X . . . elastic filmstretchable structure, 21 . . . side seal portion, 23 . . . waist endportion region, 24 . . . waist end portion elastic member, 25 . . .contraction wrinkle, 29 . . . leg line, 30 . . . elastic film, 31 . . .through hole, 40 . . . sheet bond portion, 70 . . . non-stretchableregion, 80 . . . stretchable region.

The invention claimed is:
 1. An absorbent article having an absorberthat absorbs excrement, the absorbent article comprising: an elasticfilm stretchable structure in which an elastic film is stacked between afirst sheet layer and a second sheet layer, wherein a region having theelastic film stretchable structure includes a non-stretchable region anda stretchable region provided at least at one side of the stretchableregion in a stretching and contracting direction and being stretchablein the stretching and contracting direction, in the stretchable region,in a state in which the elastic film is stretched in the stretching andcontracting direction along surfaces of the first sheet layer and thesecond sheet layer, an elongation at an elastic limit in the stretchingand contracting direction is set to 200% or more by directly orindirectly joining the first sheet layer and the second sheet layer at alarge number of sheet bond portions arranged at intervals in each of thestretching and contracting direction and a direction orthogonal thereto,and in the non-stretchable region, in a state in which the elastic filmis stretched in the stretching and contracting direction along thesurfaces of the first sheet layer and the second sheet layer, anelongation at an elastic limit is set to 130% or less by directly orindirectly joining the first sheet layer and the second sheet layer at alarge number of sheet bond portions arranged at intervals in each of thestretching and contracting direction and the direction orthogonalthereto and at least one of by an area rate of the sheet bond portionsin the non-stretchable region being higher than that in the stretchableregion; the elastic film being melted; and the elastic film being finelydivided at least in the stretching and contracting direction, whereinthe first sheet layer and the second sheet layer are joined by way ofthrough holes formed in an elastic sheet layer at the sheet bondportions, wherein each individual through hole is wider than each sheetbond portion in a width direction, leaving gaps between an edge of theindividual through hole and an edge of the individual sheet bond portionwithin the through hole.
 2. The absorbent article according to claim 1,wherein a display portion composed of the sheet bond portions formed bydirectly or indirectly joining the first sheet layer and the secondsheet layer is included in a middle in the direction orthogonal to thestretching and contracting direction, and neither side of thenon-stretchable region in the direction orthogonal to the stretching andcontracting direction is provided with the stretchable region.
 3. Theabsorbent article according to claim 2, wherein the sheet bond portionsare formed by welding materials of the first sheet layer and the secondsheet layer.
 4. The absorbent article according to claim 2, wherein inthe non-stretchable region, the area rate of the sheet bond portions ishigher than that in the stretchable region so that an elongation at anelastic limit in the stretching and contracting direction is set to 130%or less, an area of each of the sheet bond portions is in a range of0.14 to 3.5 mm², in the non-stretchable region, the area rate of thesheet bond portions is in a range of 16 to 45%, and in the stretchableregion, the area rate of the sheet bond portions is in a range of 1.8 to22.5%.
 5. The absorbent article according to claim 2, wherein theabsorbent article is an underpants-type disposable diaper comprising: anouter body provided in a front body and a back body, an inner body fixedto an internal surface of the outer body and comprising an absorber,wherein both side portions of the front body of the outer body arerespectively joined to both side portions of the back body of the outerbody to define side seal portions, and an annular torso region, a waistopening, and a pair of right and left leg openings are thereby formed,at least one of the front body and the back body comprises the regionhaving the elastic film stretchable structure, the region being disposedacross a width direction range corresponding to a range between both theside seal portions at least in a part of a front-back direction range ofthe side seal portions such that the stretching and contractingdirection of the elastic film stretchable structure corresponds to awidth direction.
 6. The absorbent article according to claim 5, whereinthe outer body in at least one of the front body and the back bodycomprises a torso intermediate region defined as a front-back directionrange between a waist end portion region and the absorber, and theelastic film stretchable structure is provided across a width directionrange corresponding to the range between both the side seal portions atleast in the torso intermediate region such that the stretching andcontracting direction thereof corresponds to the width direction, andthe torso intermediate region is set to include in an intermediateportion in the width direction, the non-stretchable region having thedisplay portion, and the stretchable region in a width direction rangecorresponding to a range between the non-stretchable region and the sideseal portion.
 7. The absorbent article according to claim 6, wherein thetorso region of the outer body included at least in one of the frontbody and the back body includes an absorber region overlapping theabsorber, and the elastic film stretchable structure disposed across awhole of the width direction at least of a region from the torsointermediate region to the absorber region such that the stretching andcontracting direction of the elastic film stretchable structurecorresponds to a width direction, and the region from the torsointermediate region to the absorber region is set to have thenon-stretchable region having the display portion in an intermediateportion in the width direction thereof, and the stretchable region at awidth direction range corresponding to a range between thenon-stretchable region and the side seal portion.
 8. The absorbentarticle according to claim 6, wherein the elastic film stretchablestructure is extended to the waist end portion region, and another noother stretchable structure stretchable in a width direction is providedat a front and a back of the non-stretchable region.
 9. The absorbentarticle according to claim 6, wherein a whole width direction rangecorresponding to a range between the both side seal portions in thewaist end portion region is set to the stretchable region in which anelongated waist end portion elastic member is fixed in a stretched statealong the width direction.
 10. The absorbent article according to claim6, wherein in the waist end portion region, a width direction rangecorresponding to the stretchable region is set to an area in which anelongated waist end portion elastic member is fixed in a stretched statealong the width direction, and in the waist end portion region, a widthdirection range corresponding at least to the display portion is set toan area in which an elongation at an elastic limit is smaller than thatof the stretchable region in the waist end portion region.
 11. Theabsorbent article according to claim 6, wherein the non-stretchableregion is set to have any one of (a) a shape in which a width becomessmaller continuously or stepwise as progressing toward a waist openingside from a crotch side, (b) a shape in which the width becomes largercontinuously or stepwise as progressing toward the waist opening sidefrom the crotch side, and (c) a shape in which the width becomes oncelarger and after that becomes smaller continuously or stepwise asprogressing toward the waist opening side from the crotch side.
 12. Theabsorbent article according to claim 6, wherein the non-stretchableregion has a shape branched into a plurality of parts as progressingtoward a waist opening side from a crotch side, and the stretchableregion is provided between the two adjacent branched parts of thenon-stretchable region.